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Expressions
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<TR><TD BGCOLOR="#66ff66"><DIV ALIGN=center><TABLE>
<TR><TD><A NAME="htoc65"><B><FONT SIZE=5>6.7</FONT></B></A></TD>
<TD WIDTH="100%" ALIGN=center><B><FONT SIZE=5>Expressions</FONT></B></TD>
</TR></TABLE></DIV></TD>
</TR></TABLE> <A NAME="s:value-expr"></A>
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<DIV ALIGN=center><TABLE CELLSPACING=2 CELLPADDING=0>
<TR><TD ALIGN=right NOWRAP>
<TT><I><FONT COLOR=maroon>expr</FONT></I></TT></TD>
<TD ALIGN=right NOWRAP>::=</TD>
<TD ALIGN=left NOWRAP>
<TT><I><FONT COLOR=maroon>value-path</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><I><FONT COLOR=maroon>constant</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>(</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>)</FONT></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>begin</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>end</FONT></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>(</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>:</FONT></TT> <TT><I><FONT COLOR=maroon>typexpr</FONT></I></TT> <TT><FONT COLOR=blue>)</FONT></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>,</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> { <TT><FONT COLOR=blue>,</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> }</TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><I><FONT COLOR=maroon>ncconstr</FONT></I></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>`</FONT></TT><TT><I><FONT COLOR=maroon>tag-name</FONT></I></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>::</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>[</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> { <TT><FONT COLOR=blue>;</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> } <TT><FONT COLOR=blue>]</FONT></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>[|</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> { <TT><FONT COLOR=blue>;</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> } <TT><FONT COLOR=blue>|]</FONT></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>{</FONT></TT> <TT><I><FONT COLOR=maroon>field</FONT></I></TT> <TT><FONT COLOR=blue>=</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> { <TT><FONT COLOR=blue>;</FONT></TT> <TT><I><FONT COLOR=maroon>field</FONT></I></TT> <TT><FONT COLOR=blue>=</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> } <TT><FONT COLOR=blue>}</FONT></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>{</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>with</FONT></TT> <TT><I><FONT COLOR=maroon>field</FONT></I></TT> <TT><FONT COLOR=blue>=</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> { <TT><FONT COLOR=blue>;</FONT></TT> <TT><I><FONT COLOR=maroon>field</FONT></I></TT> <TT><FONT COLOR=blue>=</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> } <TT><FONT COLOR=blue>}</FONT></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> { <TT><I><FONT COLOR=maroon>argument</FONT></I></TT> }<SUP><FONT SIZE=2>+</FONT></SUP></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><I><FONT COLOR=maroon>prefix-symbol</FONT></I></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><I><FONT COLOR=maroon>infix-op</FONT></I></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>.</FONT></TT> <TT><I><FONT COLOR=maroon>field</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>.</FONT></TT> <TT><I><FONT COLOR=maroon>field</FONT></I></TT> <TT><FONT COLOR=blue><-</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>.(</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>)</FONT></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>.(</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>)</FONT></TT> <TT><FONT COLOR=blue><-</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>.[</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>]</FONT></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>.[</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>]</FONT></TT> <TT><FONT COLOR=blue><-</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>if</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>then</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> [ <TT><FONT COLOR=blue>else</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> ]</TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>while</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>do</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>done</FONT></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>for</FONT></TT> <TT><I><FONT COLOR=maroon>ident</FONT></I></TT> <TT><FONT COLOR=blue>=</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> ( <TT><FONT COLOR=blue>to</FONT></TT> | <TT><FONT COLOR=blue>downto</FONT></TT> ) <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>do</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>done</FONT></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>;</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>match</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>with</FONT></TT> <TT><I><FONT COLOR=maroon>pattern-matching</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>function</FONT></TT> <TT><I><FONT COLOR=maroon>pattern-matching</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>fun</FONT></TT> <TT><I><FONT COLOR=maroon>multiple-matching</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>try</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>with</FONT></TT> <TT><I><FONT COLOR=maroon>pattern-matching</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>let</FONT></TT> [<TT><FONT COLOR=blue>rec</FONT></TT>] <TT><I><FONT COLOR=maroon>let-binding</FONT></I></TT> { <TT><FONT COLOR=blue>and</FONT></TT> <TT><I><FONT COLOR=maroon>let-binding</FONT></I></TT> } <TT><FONT COLOR=blue>in</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>new</FONT></TT> <TT><I><FONT COLOR=maroon>class-path</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>#</FONT></TT> <TT><I><FONT COLOR=maroon>method-name</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>(</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>:></FONT></TT> <TT><I><FONT COLOR=maroon>typexpr</FONT></I></TT> <TT><FONT COLOR=blue>)</FONT></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>(</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>:</FONT></TT> <TT><I><FONT COLOR=maroon>typexpr</FONT></I></TT> <TT><FONT COLOR=blue>:></FONT></TT> <TT><I><FONT COLOR=maroon>typexpr</FONT></I></TT> <TT><FONT COLOR=blue>)</FONT></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>{<</FONT></TT> <TT><I><FONT COLOR=maroon>inst-var-name</FONT></I></TT> <TT><FONT COLOR=blue>=</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> { <TT><FONT COLOR=blue>;</FONT></TT> <TT><I><FONT COLOR=maroon>inst-var-name</FONT></I></TT> <TT><FONT COLOR=blue>=</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> } <TT><FONT COLOR=blue>>}</FONT></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP>
<TT><I><FONT COLOR=maroon>argument</FONT></I></TT></TD>
<TD ALIGN=right NOWRAP>::=</TD>
<TD ALIGN=left NOWRAP>
<TT><I><FONT COLOR=maroon>expr</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>~</FONT></TT> <TT><I><FONT COLOR=maroon>label-name</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>~</FONT></TT> <TT><I><FONT COLOR=maroon>label-name</FONT></I></TT> <TT><FONT COLOR=blue>:</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>?</FONT></TT> <TT><I><FONT COLOR=maroon>label-name</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>?</FONT></TT> <TT><I><FONT COLOR=maroon>label-name</FONT></I></TT> <TT><FONT COLOR=blue>:</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT></TD>
</TR></TABLE></DIV>
<DIV ALIGN=center><TABLE CELLSPACING=2 CELLPADDING=0>
<TR><TD ALIGN=right NOWRAP>
<TT><I><FONT COLOR=maroon>pattern-matching</FONT></I></TT></TD>
<TD ALIGN=right NOWRAP>::=</TD>
<TD ALIGN=left NOWRAP>
[ <TT><FONT COLOR=blue>|</FONT></TT> ] <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT> [<TT><FONT COLOR=blue>when</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT>] <TT><FONT COLOR=blue>-></FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT>
{ <TT><FONT COLOR=blue>|</FONT></TT> <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT> [<TT><FONT COLOR=blue>when</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT>] <TT><FONT COLOR=blue>-></FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> }</TD>
</TR>
<TR><TD ALIGN=right NOWRAP>
<TT><I><FONT COLOR=maroon>multiple-matching</FONT></I></TT></TD>
<TD ALIGN=right NOWRAP>::=</TD>
<TD ALIGN=left NOWRAP>
{ <TT><I><FONT COLOR=maroon>parameter</FONT></I></TT> }<SUP><FONT SIZE=2>+</FONT></SUP> [<TT><FONT COLOR=blue>when</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT>] <TT><FONT COLOR=blue>-></FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP>
<TT><I><FONT COLOR=maroon>let-binding</FONT></I></TT></TD>
<TD ALIGN=right NOWRAP>::=</TD>
<TD ALIGN=left NOWRAP>
<TT><I><FONT COLOR=maroon>pattern</FONT></I></TT> [<TT><FONT COLOR=blue>:</FONT></TT> <TT><I><FONT COLOR=maroon>typexpr</FONT></I></TT>] <TT><FONT COLOR=blue>=</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><I><FONT COLOR=maroon>value-name</FONT></I></TT> { <TT><I><FONT COLOR=maroon>parameter</FONT></I></TT> }<SUP><FONT SIZE=2>+</FONT></SUP> [<TT><FONT COLOR=blue>:</FONT></TT> <TT><I><FONT COLOR=maroon>typexpr</FONT></I></TT>] <TT><FONT COLOR=blue>=</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP>
<TT><I><FONT COLOR=maroon>parameter</FONT></I></TT></TD>
<TD ALIGN=right NOWRAP>::=</TD>
<TD ALIGN=left NOWRAP>
<TT><I><FONT COLOR=maroon>pattern</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>~</FONT></TT> <TT><I><FONT COLOR=maroon>label-name</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>~</FONT></TT> <TT><FONT COLOR=blue>(</FONT></TT> <TT><I><FONT COLOR=maroon>label-name</FONT></I></TT> [<TT><FONT COLOR=blue>:</FONT></TT> <TT><I><FONT COLOR=maroon>typexpr</FONT></I></TT>] <TT><FONT COLOR=blue>)</FONT></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>~</FONT></TT> <TT><I><FONT COLOR=maroon>label-name</FONT></I></TT> <TT><FONT COLOR=blue>:</FONT></TT> <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>?</FONT></TT> <TT><I><FONT COLOR=maroon>label-name</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>?</FONT></TT> <TT><FONT COLOR=blue>(</FONT></TT> <TT><I><FONT COLOR=maroon>label-name</FONT></I></TT> [<TT><FONT COLOR=blue>:</FONT></TT> <TT><I><FONT COLOR=maroon>typexpr</FONT></I></TT>] [<TT><FONT COLOR=blue>=</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT>] <TT><FONT COLOR=blue>)</FONT></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>?</FONT></TT> <TT><I><FONT COLOR=maroon>label-name</FONT></I></TT> <TT><FONT COLOR=blue>:</FONT></TT> <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>?</FONT></TT> <TT><I><FONT COLOR=maroon>label-name</FONT></I></TT> <TT><FONT COLOR=blue>:</FONT></TT> <TT><FONT COLOR=blue>(</FONT></TT> <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT> [<TT><FONT COLOR=blue>:</FONT></TT> <TT><I><FONT COLOR=maroon>typexpr</FONT></I></TT>] [<TT><FONT COLOR=blue>=</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT>] <TT><FONT COLOR=blue>)</FONT></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP>
<TT><I><FONT COLOR=maroon>infix-op</FONT></I></TT></TD>
<TD ALIGN=right NOWRAP>::=</TD>
<TD ALIGN=left NOWRAP>
<TT><I><FONT COLOR=maroon>infix-symbol</FONT></I></TT></TD>
</TR>
<TR><TD ALIGN=right NOWRAP> </TD>
<TD ALIGN=right NOWRAP>|</TD>
<TD ALIGN=left NOWRAP> <TT><FONT COLOR=blue>*</FONT></TT> | <TT><FONT COLOR=blue>=</FONT></TT> | <TT><FONT COLOR=blue>or</FONT></TT> | <TT><FONT COLOR=blue>&</FONT></TT></TD>
</TR></TABLE></DIV><BR>
The table below shows the relative precedences and associativity of
operators and non-closed constructions. The constructions with higher
precedence come first. For infix and prefix symbols, we write
``<TT>*</TT>...'' to mean ``any symbol starting with <TT>*</TT>''.
<A NAME="@manual.kwd31"></A><A NAME="@manual.kwd32"></A><A NAME="@manual.kwd33"></A><A NAME="@manual.kwd34"></A><A NAME="@manual.kwd35"></A><A NAME="@manual.kwd36"></A><A NAME="@manual.kwd37"></A><A NAME="@manual.kwd38"></A><BR>
<DIV ALIGN=center><TABLE BORDER=1 CELLSPACING=0 CELLPADDING=1 WIDTH="80%">
<TR><TD ALIGN=center NOWRAP><B>Construction or operator</B></TD>
<TD ALIGN=center NOWRAP><B>Associativity</B></TD>
</TR>
<TR><TD ALIGN=left NOWRAP>
prefix-symbol</TD>
<TD ALIGN=left NOWRAP>--</TD>
</TR>
<TR><TD ALIGN=left NOWRAP><TT>. .( .[</TT></TD>
<TD ALIGN=left NOWRAP>--</TD>
</TR>
<TR><TD ALIGN=left NOWRAP>function application</TD>
<TD ALIGN=left NOWRAP>left</TD>
</TR>
<TR><TD ALIGN=left NOWRAP>constructor application</TD>
<TD ALIGN=left NOWRAP>--</TD>
</TR>
<TR><TD ALIGN=left NOWRAP><TT>- -.</TT> (prefix)</TD>
<TD ALIGN=left NOWRAP>--</TD>
</TR>
<TR><TD ALIGN=left NOWRAP><TT>**</TT>...</TD>
<TD ALIGN=left NOWRAP>right</TD>
</TR>
<TR><TD ALIGN=left NOWRAP><TT>*</TT>...<TT> /</TT>...<TT> %</TT>...<TT> mod</TT></TD>
<TD ALIGN=left NOWRAP>left</TD>
</TR>
<TR><TD ALIGN=left NOWRAP><TT>+</TT>...<TT> -</TT>...</TD>
<TD ALIGN=left NOWRAP>left</TD>
</TR>
<TR><TD ALIGN=left NOWRAP><TT>::</TT></TD>
<TD ALIGN=left NOWRAP>right</TD>
</TR>
<TR><TD ALIGN=left NOWRAP><TT>@</TT>...<TT>^</TT>...</TD>
<TD ALIGN=left NOWRAP>right</TD>
</TR>
<TR><TD ALIGN=left NOWRAP>comparisons (<TT>= == < </TT> etc.), all other infix symbols</TD>
<TD ALIGN=left NOWRAP>left</TD>
</TR>
<TR><TD ALIGN=left NOWRAP><TT>not</TT></TD>
<TD ALIGN=left NOWRAP>--</TD>
</TR>
<TR><TD ALIGN=left NOWRAP><TT>& &&</TT></TD>
<TD ALIGN=left NOWRAP>left</TD>
</TR>
<TR><TD ALIGN=left NOWRAP><TT>or ||</TT></TD>
<TD ALIGN=left NOWRAP>left</TD>
</TR>
<TR><TD ALIGN=left NOWRAP><TT>,</TT></TD>
<TD ALIGN=left NOWRAP>--</TD>
</TR>
<TR><TD ALIGN=left NOWRAP><TT><- :=</TT></TD>
<TD ALIGN=left NOWRAP>right</TD>
</TR>
<TR><TD ALIGN=left NOWRAP><TT>if</TT></TD>
<TD ALIGN=left NOWRAP>--</TD>
</TR>
<TR><TD ALIGN=left NOWRAP><TT>;</TT></TD>
<TD ALIGN=left NOWRAP>right</TD>
</TR>
<TR><TD ALIGN=left NOWRAP><TT>let match fun function try</TT></TD>
<TD ALIGN=left NOWRAP>--</TD>
</TR></TABLE></DIV><BR>
<TABLE CELLPADDING=0 CELLSPACING=0 WIDTH="100%">
<TR><TD BGCOLOR="#7fff7f"><DIV ALIGN=center><TABLE>
<TR><TD><A NAME="htoc66"><B><FONT SIZE=4>6.7.1</FONT></B></A></TD>
<TD WIDTH="100%" ALIGN=center><B><FONT SIZE=4>Basic expressions</FONT></B></TD>
</TR></TABLE></DIV></TD>
</TR></TABLE><BR>
<TABLE CELLPADDING=0 CELLSPACING=0 WIDTH="100%">
<TR><TD BGCOLOR="#98ff98"><DIV ALIGN=center><TABLE>
<TR><TD><B>Constants</B></TD>
</TR></TABLE></DIV></TD>
</TR></TABLE><BR>
Expressions consisting in a constant evaluate to this constant.<BR>
<BR>
<TABLE CELLPADDING=0 CELLSPACING=0 WIDTH="100%">
<TR><TD BGCOLOR="#98ff98"><DIV ALIGN=center><TABLE>
<TR><TD><B>Value paths</B></TD>
</TR></TABLE></DIV></TD>
</TR></TABLE> <A NAME="expr:var"></A><BR>
Expressions consisting in an access path evaluate to the value bound to
this path in the current evaluation environment. The path can
be either a value name or an access path to a value component of a module.<BR>
<BR>
<TABLE CELLPADDING=0 CELLSPACING=0 WIDTH="100%">
<TR><TD BGCOLOR="#98ff98"><DIV ALIGN=center><TABLE>
<TR><TD><B>Parenthesized expressions</B></TD>
</TR></TABLE></DIV></TD>
</TR></TABLE>
<A NAME="@manual.kwd39"></A>
<A NAME="@manual.kwd40"></A><BR>
The expressions <TT><FONT COLOR=blue>(</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>)</FONT></TT> and <TT><FONT COLOR=blue>begin</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>end</FONT></TT> have the same
value as <TT><I><FONT COLOR=maroon>expr</FONT></I></TT>. Both constructs are semantically equivalent, but it
is good style to use <TT><FONT COLOR=blue>begin</FONT></TT> ... <TT><FONT COLOR=blue>end</FONT></TT> inside control structures:
<PRE>
if ... then begin ... ; ... end else begin ... ; ... end
</PRE>
and <TT><FONT COLOR=blue>(</FONT></TT> ... <TT><FONT COLOR=blue>)</FONT></TT> for the other grouping situations.<BR>
<BR>
Parenthesized expressions can contain a type constraint, as in <TT><FONT COLOR=blue>(</FONT></TT>
<TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>:</FONT></TT> <TT><I><FONT COLOR=maroon>type</FONT></I></TT> <TT><FONT COLOR=blue>)</FONT></TT>. This constraint forces the type of <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> to be
compatible with <TT><I><FONT COLOR=maroon>type</FONT></I></TT>.<BR>
<BR>
Parenthesized expressions can also contain coercions <TT><FONT COLOR=blue>(</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> [<TT><FONT COLOR=blue>:</FONT></TT> <TT><I><FONT COLOR=maroon>type</FONT></I></TT>] <TT><FONT COLOR=blue>:></FONT></TT> <TT><I><FONT COLOR=maroon>type</FONT></I></TT><TT><FONT COLOR=blue>)</FONT></TT> (see subsection <A HREF="#s:objects">6.7.5</A> below).<BR>
<BR>
<TABLE CELLPADDING=0 CELLSPACING=0 WIDTH="100%">
<TR><TD BGCOLOR="#98ff98"><DIV ALIGN=center><TABLE>
<TR><TD><B>Function application</B></TD>
</TR></TABLE></DIV></TD>
</TR></TABLE><BR>
Function application is denoted by juxtaposition of (possibly labeled)
expressions. The expression <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><I><FONT COLOR=maroon>argument</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> ... <TT><I><FONT COLOR=maroon>argument</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB>
evaluates the expression <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> and those appearing in <TT><I><FONT COLOR=maroon>argument</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB>
to <TT><I><FONT COLOR=maroon>argument</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB>. The expression <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> must evaluate to a
functional value <TT><I><FONT COLOR=maroon>f</FONT></I></TT>, which is then applied to the values of
<TT><I><FONT COLOR=maroon>argument</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB>, ..., <TT><I><FONT COLOR=maroon>argument</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB>.<BR>
<BR>
The order in which the expressions <TT><I><FONT COLOR=maroon>expr</FONT></I></TT>, <TT><I><FONT COLOR=maroon>argument</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB>, ...,
<TT><I><FONT COLOR=maroon>argument</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB> are evaluated is not specified.<BR>
<BR>
Arguments and parameters are matched according to their respective
labels. Argument order is irrelevant, except among arguments with the
same label, or no label.<BR>
<BR>
If a parameter is specified as optional (label prefixed by <TT>?</TT>) in the
type of <TT><I><FONT COLOR=maroon>expr</FONT></I></TT>, the corresponding argument will be automatically
wrapped with the constructor <TT>Some</TT>, except if the argument itself is
also prefixed by <TT>?</TT>, in which case it is passed as is.
If a non-labeled argument is passed, and its corresponding parameter
is preceded by one or several optional parameters, then these
parameters are <EM>defaulted</EM>, <EM>i.e.</EM> the value <TT>None</TT> will be
passed for them.
All other missing parameters (without corresponding argument), both
optional and non-optional, will be kept, and the result of the
function will still be a function of these missing parameters to the
body of <TT><I><FONT COLOR=maroon>f</FONT></I></TT>.<BR>
<BR>
As a special case, if the function has a known arity, all the
arguments are unlabeled, and their number matches the number of
non-optional parameters, then labels are ignored and non-optional
parameters are matched in their definition order. Optional arguments
are defaulted.<BR>
<BR>
In all cases but exact match of order and labels, without optional
parameters, the function type should be known at the application
point. This can be ensured by adding a type constraint. Principality
of the derivation can be checked in the <TT>-principal</TT> mode.<BR>
<BR>
<TABLE CELLPADDING=0 CELLSPACING=0 WIDTH="100%">
<TR><TD BGCOLOR="#98ff98"><DIV ALIGN=center><TABLE>
<TR><TD><B>Function definition</B></TD>
</TR></TABLE></DIV></TD>
</TR></TABLE><BR>
Two syntactic forms are provided to define functions. The first form
is introduced by the keyword <TT>function</TT>:
<A NAME="@manual.kwd41"></A><BR>
<DIV ALIGN=center><TABLE CELLSPACING=2 CELLPADDING=0>
<TR><TD ALIGN=right NOWRAP><TT><FONT COLOR=blue>function</FONT></TT></TD>
<TD ALIGN=left NOWRAP><I><FONT COLOR=maroon><I>pattern</I></FONT></I><SUB><FONT SIZE=2>1</FONT></SUB></TD>
<TD ALIGN=left NOWRAP><TT><FONT COLOR=blue>-></FONT></TT></TD>
<TD ALIGN=left NOWRAP><I><FONT COLOR=maroon><I>expr</I></FONT></I><SUB><FONT SIZE=2>1</FONT></SUB></TD>
</TR>
<TR><TD ALIGN=right NOWRAP><TT><FONT COLOR=blue>|</FONT></TT></TD>
<TD ALIGN=left NOWRAP>...</TD>
</TR>
<TR><TD ALIGN=right NOWRAP><TT><FONT COLOR=blue>|</FONT></TT></TD>
<TD ALIGN=left NOWRAP><I><FONT COLOR=maroon><I>pattern</I></FONT></I><SUB><FONT SIZE=2><I>n</I></FONT></SUB></TD>
<TD ALIGN=left NOWRAP><TT><FONT COLOR=blue>-></FONT></TT></TD>
<TD ALIGN=left NOWRAP><I><FONT COLOR=maroon><I>expr</I></FONT></I><SUB><FONT SIZE=2><I>n</I></FONT></SUB></TD>
</TR></TABLE></DIV>
This expression evaluates to a functional value with one argument.
When this function is applied to a value <I>v</I>, this value is
matched against each pattern <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> to <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB>.
If one of these matchings succeeds, that is, if the value <I>v</I>
matches the pattern <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT><SUB><FONT SIZE=2><I>i</I></FONT></SUB> for some <I>i</I>,
then the expression <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2><I>i</I></FONT></SUB> associated to the selected pattern
is evaluated, and its value becomes the value of the function
application. The evaluation of <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2><I>i</I></FONT></SUB> takes place in an
environment enriched by the bindings performed during the matching.<BR>
<BR>
If several patterns match the argument <I>v</I>, the one that occurs
first in the function definition is selected. If none of the patterns
matches the argument, the exception <TT>Match_failure</TT> is raised.
<A NAME="@manual0"></A><BR>
<BR>
<BR>
<BR>
<BR>
The other form of function definition is introduced by the keyword <TT>fun</TT>:
<A NAME="@manual.kwd42"></A>
<DIV ALIGN=center>
<TT><FONT COLOR=blue>fun</FONT></TT> <TT><I><FONT COLOR=maroon>parameter</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> ... <TT><I><FONT COLOR=maroon>parameter</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB> <TT><FONT COLOR=blue>-></FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT>
</DIV>
This expression is equivalent to:
<DIV ALIGN=center>
<TT><FONT COLOR=blue>fun</FONT></TT> <TT><I><FONT COLOR=maroon>parameter</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>-></FONT></TT> ... <TT><FONT COLOR=blue>fun</FONT></TT> <TT><I><FONT COLOR=maroon>parameter</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB> <TT><FONT COLOR=blue>-></FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT>
</DIV>
Functions of the form <TT><FONT COLOR=blue>fun</FONT></TT> <TT><I><FONT COLOR=maroon>optlabel</FONT></I></TT> <TT><FONT COLOR=blue>(</FONT></TT> <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT> <TT><FONT COLOR=blue>=</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>0</FONT></SUB> <TT><FONT COLOR=blue>)</FONT></TT> <TT><FONT COLOR=blue>-></FONT></TT>
<TT><I><FONT COLOR=maroon>expr</FONT></I></TT> are equivalent to
<DIV ALIGN=center><TABLE CELLSPACING=2 CELLPADDING=0>
<TR><TD ALIGN=right NOWRAP>
<TT><FONT COLOR=blue>fun</FONT></TT> <TT><I><FONT COLOR=maroon>optlabel</FONT></I></TT> <TT><I><FONT COLOR=maroon>x</FONT></I></TT> <TT><FONT COLOR=blue>-></FONT></TT>
<TT><FONT COLOR=blue>let</FONT></TT> <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT> <TT><FONT COLOR=blue>=</FONT></TT>
<TT><FONT COLOR=blue>match</FONT></TT> <TT><I><FONT COLOR=maroon>x</FONT></I></TT> <TT><FONT COLOR=blue>with</FONT></TT> <TT><FONT COLOR=blue>Some</FONT></TT> <TT><I><FONT COLOR=maroon>x</FONT></I></TT> <TT><FONT COLOR=blue>-></FONT></TT> <TT><I><FONT COLOR=maroon>x</FONT></I></TT> <TT><FONT COLOR=blue>|</FONT></TT> <TT><FONT COLOR=blue>None</FONT></TT> <TT><FONT COLOR=blue>-></FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>0</FONT></SUB>
<TT><FONT COLOR=blue>in</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT></TD>
</TR></TABLE></DIV>
where <TT><I><FONT COLOR=maroon>x</FONT></I></TT> is a fresh variable. When <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>0</FONT></SUB> will be evaluated is left
unspecified.<BR>
<BR>
After these two transformations, expressions are of the form
<DIV ALIGN=center>
<TT><FONT COLOR=blue>fun</FONT></TT> [<TT><I><FONT COLOR=maroon>label</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB>] <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>-></FONT></TT> ... <TT><FONT COLOR=blue>fun</FONT></TT> [<TT><I><FONT COLOR=maroon>label</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB>] <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB> <TT><FONT COLOR=blue>-></FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT>
</DIV>
If we ignore labels, which will only be meaningful at function
application, this is equivalent to
<DIV ALIGN=center>
<TT><FONT COLOR=blue>function</FONT></TT> <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>-></FONT></TT> ... <TT><FONT COLOR=blue>function</FONT></TT> <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB> <TT><FONT COLOR=blue>-></FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT>
</DIV>
That is, the <TT>fun</TT> expression above evaluates to a curried function
with <I>n</I> arguments: after applying this function <I>n</I> times to the
values <I>v</I><SUB><FONT SIZE=2>1</FONT></SUB> ... <I>v</I><SUB><FONT SIZE=2><I>m</I></FONT></SUB>, the values will be matched
in parallel against the patterns <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> ... <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB>.
If the matching succeeds, the function returns the value of <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> in
an environment enriched by the bindings performed during the matchings.
If the matching fails, the exception <TT>Match_failure</TT> is raised.<BR>
<BR>
<TABLE CELLPADDING=0 CELLSPACING=0 WIDTH="100%">
<TR><TD BGCOLOR="#98ff98"><DIV ALIGN=center><TABLE>
<TR><TD><B>Guards in pattern-matchings</B></TD>
</TR></TABLE></DIV></TD>
</TR></TABLE><BR>
<A NAME="@manual.kwd43"></A>
Cases of a pattern matching (in the <TT>function</TT>, <TT>fun</TT>, <TT>match</TT> and
<TT>try</TT> constructs) can include guard expressions, which are
arbitrary boolean expressions that must evaluate to <TT>true</TT> for the
match case to be selected. Guards occur just before the <TT>-></TT> token and
are introduced by the <TT>when</TT> keyword:<BR>
<DIV ALIGN=center><TABLE CELLSPACING=2 CELLPADDING=0>
<TR><TD ALIGN=right NOWRAP><TT><FONT COLOR=blue>function</FONT></TT></TD>
<TD ALIGN=left NOWRAP><I><FONT COLOR=maroon><I>pattern</I></FONT></I><SUB><FONT SIZE=2>1</FONT></SUB> [<TT><FONT COLOR=blue>when</FONT></TT> <I><FONT COLOR=maroon><I>cond</I></FONT></I><SUB><FONT SIZE=2>1</FONT></SUB>]</TD>
<TD ALIGN=left NOWRAP><TT><FONT COLOR=blue>-></FONT></TT></TD>
<TD ALIGN=left NOWRAP><I><FONT COLOR=maroon><I>expr</I></FONT></I><SUB><FONT SIZE=2>1</FONT></SUB></TD>
</TR>
<TR><TD ALIGN=right NOWRAP><TT><FONT COLOR=blue>|</FONT></TT></TD>
<TD ALIGN=left NOWRAP>...</TD>
</TR>
<TR><TD ALIGN=right NOWRAP><TT><FONT COLOR=blue>|</FONT></TT></TD>
<TD ALIGN=left NOWRAP><I><FONT COLOR=maroon><I>pattern</I></FONT></I><SUB><FONT SIZE=2><I>n</I></FONT></SUB> [<TT><FONT COLOR=blue>when</FONT></TT> <I><FONT COLOR=maroon><I>cond</I></FONT></I><SUB><FONT SIZE=2><I>n</I></FONT></SUB>]</TD>
<TD ALIGN=left NOWRAP><TT><FONT COLOR=blue>-></FONT></TT></TD>
<TD ALIGN=left NOWRAP><I><FONT COLOR=maroon><I>expr</I></FONT></I><SUB><FONT SIZE=2><I>n</I></FONT></SUB></TD>
</TR></TABLE></DIV><BR>
Matching proceeds as described before, except that if the value
matches some pattern <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT><SUB><FONT SIZE=2><I>i</I></FONT></SUB> which has a guard <TT><I><FONT COLOR=maroon>cond</FONT></I></TT><SUB><FONT SIZE=2><I>i</I></FONT></SUB>, then the
expression <TT><I><FONT COLOR=maroon>cond</FONT></I></TT><SUB><FONT SIZE=2><I>i</I></FONT></SUB> is evaluated (in an environment enriched by the
bindings performed during matching). If <TT><I><FONT COLOR=maroon>cond</FONT></I></TT><SUB><FONT SIZE=2><I>i</I></FONT></SUB> evaluates to <TT>true</TT>,
then <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2><I>i</I></FONT></SUB> is evaluated and its value returned as the result of the
matching, as usual. But if <TT><I><FONT COLOR=maroon>cond</FONT></I></TT><SUB><FONT SIZE=2><I>i</I></FONT></SUB> evaluates to <TT>false</TT>, the matching
is resumed against the patterns following <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT><SUB><FONT SIZE=2><I>i</I></FONT></SUB>.<BR>
<BR>
<TABLE CELLPADDING=0 CELLSPACING=0 WIDTH="100%">
<TR><TD BGCOLOR="#98ff98"><DIV ALIGN=center><TABLE>
<TR><TD><B>Local definitions</B></TD>
</TR></TABLE></DIV></TD>
</TR></TABLE> <A NAME="s:localdef"></A><BR>
<A NAME="@manual.kwd44"></A><BR>
The <TT>let</TT> and <TT>let rec</TT> constructs bind value names locally.
The construct
<DIV ALIGN=center>
<TT><FONT COLOR=blue>let</FONT></TT> <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>=</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>and</FONT></TT> ... <TT><FONT COLOR=blue>and</FONT></TT> <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB> <TT><FONT COLOR=blue>=</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB> <TT><FONT COLOR=blue>in</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT>
</DIV>
evaluates <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> ... <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB> in some unspecified order, then matches
their values against the patterns <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> ... <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB>. If the
matchings succeed, <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> is evaluated in the environment enriched by
the bindings performed during matching, and the value of <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> is
returned as the value of the whole <TT>let</TT> expression. If one of the
matchings fails, the exception <TT>Match_failure</TT> is raised.
<A NAME="@manual1"></A><BR>
<BR>
An alternate syntax is provided to bind variables to functional
values: instead of writing
<DIV ALIGN=center>
<TT><FONT COLOR=blue>let</FONT></TT> <TT><I><FONT COLOR=maroon>ident</FONT></I></TT> <TT><FONT COLOR=blue>=</FONT></TT> <TT><FONT COLOR=blue>fun</FONT></TT> <TT><I><FONT COLOR=maroon>parameter</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> ... <TT><I><FONT COLOR=maroon>parameter</FONT></I></TT><SUB><FONT SIZE=2><I>m</I></FONT></SUB> <TT><FONT COLOR=blue>-></FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT>
</DIV>
in a <TT>let</TT> expression, one may instead write
<DIV ALIGN=center>
<TT><FONT COLOR=blue>let</FONT></TT> <TT><I><FONT COLOR=maroon>ident</FONT></I></TT> <TT><I><FONT COLOR=maroon>parameter</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> ... <TT><I><FONT COLOR=maroon>parameter</FONT></I></TT><SUB><FONT SIZE=2><I>m</I></FONT></SUB> <TT><FONT COLOR=blue>=</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT>
</DIV><BR>
<BR>
Recursive definitions of names are introduced by <TT>let rec</TT>:
<DIV ALIGN=center>
<TT><FONT COLOR=blue>let</FONT></TT> <TT><FONT COLOR=blue>rec</FONT></TT> <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>=</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>and</FONT></TT> ... <TT><FONT COLOR=blue>and</FONT></TT> <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB> <TT><FONT COLOR=blue>=</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB>
<TT><FONT COLOR=blue>in</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT>
</DIV>
The only difference with the <TT>let</TT> construct described above is
that the bindings of names to values performed by the
pattern-matching are considered already performed when the expressions
<TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> to <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB> are evaluated. That is, the expressions <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB>
to <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB> can reference identifiers that are bound by one of the
patterns <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB>, ..., <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB>, and expect them to have the
same value as in <TT><I><FONT COLOR=maroon>expr</FONT></I></TT>, the body of the <TT>let rec</TT> construct.<BR>
<BR>
The recursive definition is guaranteed to behave as described above if
the expressions <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> to <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB> are function definitions
(<TT><FONT COLOR=blue>fun</FONT></TT> ... or <TT><FONT COLOR=blue>function</FONT></TT> ...), and the patterns <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB>
... <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB> are just value names, as in:
<DIV ALIGN=center>
<TT><FONT COLOR=blue>let</FONT></TT> <TT><FONT COLOR=blue>rec</FONT></TT> <TT><I><FONT COLOR=maroon>name</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>=</FONT></TT> <TT><FONT COLOR=blue>fun</FONT></TT> ...
<TT><FONT COLOR=blue>and</FONT></TT> ...
<TT><FONT COLOR=blue>and</FONT></TT> <TT><I><FONT COLOR=maroon>name</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB> <TT><FONT COLOR=blue>=</FONT></TT> <TT><FONT COLOR=blue>fun</FONT></TT> ...
<TT><FONT COLOR=blue>in</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT>
</DIV>
This defines <TT><I><FONT COLOR=maroon>name</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> ... <TT><I><FONT COLOR=maroon>name</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB> as mutually recursive functions
local to <TT><I><FONT COLOR=maroon>expr</FONT></I></TT>. <BR>
<BR>
The behavior of other forms of <TT>let rec</TT> definitions is
implementation-dependent. The current implementation also supports
a certain class of recursive definitions of non-functional values,
such as
<DIV ALIGN=center>
<TT><FONT COLOR=blue>let</FONT></TT> <TT><FONT COLOR=blue>rec</FONT></TT> <TT><I><FONT COLOR=maroon>name</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>=</FONT></TT> <TT><FONT COLOR=blue>1</FONT></TT> <TT><FONT COLOR=blue>::</FONT></TT> <TT><I><FONT COLOR=maroon>name</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB>
<TT><FONT COLOR=blue>and</FONT></TT> <TT><I><FONT COLOR=maroon>name</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> <TT><FONT COLOR=blue>=</FONT></TT> <TT><FONT COLOR=blue>2</FONT></TT> <TT><FONT COLOR=blue>::</FONT></TT> <TT><I><FONT COLOR=maroon>name</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB>
<TT><FONT COLOR=blue>in</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT>
</DIV>
which binds <TT><I><FONT COLOR=maroon>name</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> to the cyclic list <TT>1::2::1::2::</TT>..., and
<TT><I><FONT COLOR=maroon>name</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> to the cyclic list <TT>2::1::2::1::</TT>...Informally, the class of accepted definitions consists of those
definitions where the defined names occur only inside function
bodies or as argument to a data constructor.<BR>
<BR>
<TABLE CELLPADDING=0 CELLSPACING=0 WIDTH="100%">
<TR><TD BGCOLOR="#7fff7f"><DIV ALIGN=center><TABLE>
<TR><TD><A NAME="htoc67"><B><FONT SIZE=4>6.7.2</FONT></B></A></TD>
<TD WIDTH="100%" ALIGN=center><B><FONT SIZE=4>Control structures</FONT></B></TD>
</TR></TABLE></DIV></TD>
</TR></TABLE><BR>
<TABLE CELLPADDING=0 CELLSPACING=0 WIDTH="100%">
<TR><TD BGCOLOR="#98ff98"><DIV ALIGN=center><TABLE>
<TR><TD><B>Sequence</B></TD>
</TR></TABLE></DIV></TD>
</TR></TABLE><BR>
The expression <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>;</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> evaluates <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> first, then
<TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB>, and returns the value of <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB>.<BR>
<BR>
<TABLE CELLPADDING=0 CELLSPACING=0 WIDTH="100%">
<TR><TD BGCOLOR="#98ff98"><DIV ALIGN=center><TABLE>
<TR><TD><B>Conditional</B></TD>
</TR></TABLE></DIV></TD>
</TR></TABLE>
<A NAME="@manual.kwd45"></A><BR>
The expression <TT><FONT COLOR=blue>if</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>then</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> <TT><FONT COLOR=blue>else</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>3</FONT></SUB> evaluates to
the value of <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> if <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> evaluates to the boolean <TT><FONT COLOR=blue>true</FONT></TT>,
and to the value of <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>3</FONT></SUB> if <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> evaluates to the boolean
<TT><FONT COLOR=blue>false</FONT></TT>.<BR>
<BR>
The <TT><FONT COLOR=blue>else</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>3</FONT></SUB> part can be omitted, in which case it defaults to
<TT><FONT COLOR=blue>else</FONT></TT> <TT><FONT COLOR=blue>()</FONT></TT>.<BR>
<BR>
<TABLE CELLPADDING=0 CELLSPACING=0 WIDTH="100%">
<TR><TD BGCOLOR="#98ff98"><DIV ALIGN=center><TABLE>
<TR><TD><B>Case expression</B></TD>
</TR></TABLE></DIV></TD>
</TR></TABLE><A NAME="@manual.kwd46"></A><BR>
The expression
<DIV ALIGN=center><TABLE CELLSPACING=2 CELLPADDING=0>
<TR><TD ALIGN=right NOWRAP><TT><FONT COLOR=blue>match</FONT></TT></TD>
<TD ALIGN=left NOWRAP><I><FONT COLOR=maroon><I>expr</I></FONT></I></TD>
</TR>
<TR><TD ALIGN=right NOWRAP><TT><FONT COLOR=blue>with</FONT></TT></TD>
<TD ALIGN=left NOWRAP><I><FONT COLOR=maroon><I>pattern</I></FONT></I><SUB><FONT SIZE=2>1</FONT></SUB></TD>
<TD ALIGN=left NOWRAP><TT><FONT COLOR=blue>-></FONT></TT></TD>
<TD ALIGN=left NOWRAP><I><FONT COLOR=maroon><I>expr</I></FONT></I><SUB><FONT SIZE=2>1</FONT></SUB></TD>
</TR>
<TR><TD ALIGN=right NOWRAP><TT><FONT COLOR=blue>|</FONT></TT></TD>
<TD ALIGN=left NOWRAP>...</TD>
</TR>
<TR><TD ALIGN=right NOWRAP><TT><FONT COLOR=blue>|</FONT></TT></TD>
<TD ALIGN=left NOWRAP><I><FONT COLOR=maroon><I>pattern</I></FONT></I><SUB><FONT SIZE=2><I>n</I></FONT></SUB></TD>
<TD ALIGN=left NOWRAP><TT><FONT COLOR=blue>-></FONT></TT></TD>
<TD ALIGN=left NOWRAP><I><FONT COLOR=maroon><I>expr</I></FONT></I><SUB><FONT SIZE=2><I>n</I></FONT></SUB></TD>
</TR></TABLE></DIV>
matches the value of <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> against the patterns <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> to
<TT><I><FONT COLOR=maroon>pattern</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB>. If the matching against <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT><SUB><FONT SIZE=2><I>i</I></FONT></SUB> succeeds, the
associated expression <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2><I>i</I></FONT></SUB> is evaluated, and its value becomes the
value of the whole <TT><FONT COLOR=blue>match</FONT></TT> expression. The evaluation of
<TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2><I>i</I></FONT></SUB> takes place in an environment enriched by the bindings
performed during matching. If several patterns match the value of
<TT><I><FONT COLOR=maroon>expr</FONT></I></TT>, the one that occurs first in the <TT><FONT COLOR=blue>match</FONT></TT> expression is
selected. If none of the patterns match the value of <TT><I><FONT COLOR=maroon>expr</FONT></I></TT>, the
exception <TT><FONT COLOR=blue>Match_failure</FONT></TT> is raised.
<A NAME="@manual2"></A><BR>
<BR>
<TABLE CELLPADDING=0 CELLSPACING=0 WIDTH="100%">
<TR><TD BGCOLOR="#98ff98"><DIV ALIGN=center><TABLE>
<TR><TD><B>Boolean operators</B></TD>
</TR></TABLE></DIV></TD>
</TR></TABLE><BR>
The expression <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>&&</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> evaluates to <TT><FONT COLOR=blue>true</FONT></TT> if both
<TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> and <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> evaluate to <TT><FONT COLOR=blue>true</FONT></TT>; otherwise, it evaluates to
<TT><FONT COLOR=blue>false</FONT></TT>. The first component, <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB>, is evaluated first. The
second component, <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB>, is not evaluated if the first component
evaluates to <TT><FONT COLOR=blue>false</FONT></TT>. Hence, the expression <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>&&</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> behaves
exactly as
<DIV ALIGN=center>
<TT><FONT COLOR=blue>if</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>then</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> <TT><FONT COLOR=blue>else</FONT></TT> <TT><FONT COLOR=blue>false</FONT></TT>.
</DIV><BR>
The expression <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>||</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> evaluates to <TT><FONT COLOR=blue>true</FONT></TT> if one of
<TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> and <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> evaluates to <TT><FONT COLOR=blue>true</FONT></TT>; otherwise, it evaluates to
<TT><FONT COLOR=blue>false</FONT></TT>. The first component, <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB>, is evaluated first. The
second component, <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB>, is not evaluated if the first component
evaluates to <TT><FONT COLOR=blue>true</FONT></TT>. Hence, the expression <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>||</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> behaves
exactly as
<DIV ALIGN=center>
<TT><FONT COLOR=blue>if</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>then</FONT></TT> <TT><FONT COLOR=blue>true</FONT></TT> <TT><FONT COLOR=blue>else</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB>.
</DIV><BR>
<A NAME="@manual.kwd47"></A>
The boolean operator <TT><FONT COLOR=blue>&</FONT></TT> is synonymous for <TT><FONT COLOR=blue>&&</FONT></TT>. The boolean operator
<TT><FONT COLOR=blue>or</FONT></TT> is synonymous for <TT><FONT COLOR=blue>||</FONT></TT>.<BR>
<BR>
<TABLE CELLPADDING=0 CELLSPACING=0 WIDTH="100%">
<TR><TD BGCOLOR="#98ff98"><DIV ALIGN=center><TABLE>
<TR><TD><B>Loops</B></TD>
</TR></TABLE></DIV></TD>
</TR></TABLE><BR>
<A NAME="@manual.kwd48"></A>
The expression <TT><FONT COLOR=blue>while</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>do</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> <TT><FONT COLOR=blue>done</FONT></TT> repeatedly
evaluates <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> while <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> evaluates to <TT><FONT COLOR=blue>true</FONT></TT>. The loop
condition <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> is evaluated and tested at the beginning of each
iteration. The whole <TT><FONT COLOR=blue>while</FONT></TT> ... <TT><FONT COLOR=blue>done</FONT></TT> expression evaluates to
the unit value <TT><FONT COLOR=blue>()</FONT></TT>.<BR>
<BR>
<A NAME="@manual.kwd49"></A>
The expression <TT><FONT COLOR=blue>for</FONT></TT> <TT><I><FONT COLOR=maroon>name</FONT></I></TT> <TT><FONT COLOR=blue>=</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>to</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> <TT><FONT COLOR=blue>do</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>3</FONT></SUB> <TT><FONT COLOR=blue>done</FONT></TT>
first evaluates the expressions <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> and <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> (the boundaries)
into integer values <I>n</I> and <I>p</I>. Then, the loop body <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>3</FONT></SUB> is
repeatedly evaluated in an environment where <TT><I><FONT COLOR=maroon>name</FONT></I></TT> is successively
bound to the values
<I>n</I>, <I>n</I>+1, ..., <I>p</I>-1, <I>p</I>.
The loop body is never evaluated if <I>n</I> > <I>p</I>.<BR>
<BR>
The expression <TT><FONT COLOR=blue>for</FONT></TT> <TT><I><FONT COLOR=maroon>name</FONT></I></TT> <TT><FONT COLOR=blue>=</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>downto</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> <TT><FONT COLOR=blue>do</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>3</FONT></SUB> <TT><FONT COLOR=blue>done</FONT></TT>
evaluates similarly, except that <TT><I><FONT COLOR=maroon>name</FONT></I></TT> is successively bound to the values
<I>n</I>, <I>n</I>-1, ..., <I>p</I>+1, <I>p</I>.
The loop body is never evaluated if <I>n</I> < <I>p</I>.<BR>
<BR>
In both cases, the whole <TT><FONT COLOR=blue>for</FONT></TT> expression evaluates to the unit
value <TT><FONT COLOR=blue>()</FONT></TT>.<BR>
<BR>
<TABLE CELLPADDING=0 CELLSPACING=0 WIDTH="100%">
<TR><TD BGCOLOR="#98ff98"><DIV ALIGN=center><TABLE>
<TR><TD><B>Exception handling</B></TD>
</TR></TABLE></DIV></TD>
</TR></TABLE>
<A NAME="@manual.kwd50"></A><BR>
The expression
<DIV ALIGN=center><TABLE CELLSPACING=2 CELLPADDING=0>
<TR><TD ALIGN=right NOWRAP><TT><FONT COLOR=blue>try </FONT></TT></TD>
<TD ALIGN=left NOWRAP><I><FONT COLOR=maroon><I>expr</I></FONT></I></TD>
</TR>
<TR><TD ALIGN=right NOWRAP><TT><FONT COLOR=blue>with</FONT></TT></TD>
<TD ALIGN=left NOWRAP><I><FONT COLOR=maroon><I>pattern</I></FONT></I><SUB><FONT SIZE=2>1</FONT></SUB></TD>
<TD ALIGN=left NOWRAP><TT><FONT COLOR=blue>-></FONT></TT></TD>
<TD ALIGN=left NOWRAP><I><FONT COLOR=maroon><I>expr</I></FONT></I><SUB><FONT SIZE=2>1</FONT></SUB></TD>
</TR>
<TR><TD ALIGN=right NOWRAP><TT><FONT COLOR=blue>|</FONT></TT></TD>
<TD ALIGN=left NOWRAP>...</TD>
</TR>
<TR><TD ALIGN=right NOWRAP><TT><FONT COLOR=blue>|</FONT></TT></TD>
<TD ALIGN=left NOWRAP><I><FONT COLOR=maroon><I>pattern</I></FONT></I><SUB><FONT SIZE=2><I>n</I></FONT></SUB></TD>
<TD ALIGN=left NOWRAP><TT><FONT COLOR=blue>-></FONT></TT></TD>
<TD ALIGN=left NOWRAP><I><FONT COLOR=maroon><I>expr</I></FONT></I><SUB><FONT SIZE=2><I>n</I></FONT></SUB></TD>
</TR></TABLE></DIV>
evaluates the expression <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> and returns its value if the
evaluation of <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> does not raise any exception. If the evaluation
of <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> raises an exception, the exception value is matched against
the patterns <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> to <TT><I><FONT COLOR=maroon>pattern</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB>. If the matching against
<TT><I><FONT COLOR=maroon>pattern</FONT></I></TT><SUB><FONT SIZE=2><I>i</I></FONT></SUB> succeeds, the associated expression <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2><I>i</I></FONT></SUB> is evaluated,
and its value becomes the value of the whole <TT><FONT COLOR=blue>try</FONT></TT> expression. The
evaluation of <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2><I>i</I></FONT></SUB> takes place in an environment enriched by the
bindings performed during matching. If several patterns match the value of
<TT><I><FONT COLOR=maroon>expr</FONT></I></TT>, the one that occurs first in the <TT><FONT COLOR=blue>try</FONT></TT> expression is
selected. If none of the patterns matches the value of <TT><I><FONT COLOR=maroon>expr</FONT></I></TT>, the
exception value is raised again, thereby transparently ``passing
through'' the <TT><FONT COLOR=blue>try</FONT></TT> construct.<BR>
<BR>
<TABLE CELLPADDING=0 CELLSPACING=0 WIDTH="100%">
<TR><TD BGCOLOR="#7fff7f"><DIV ALIGN=center><TABLE>
<TR><TD><A NAME="htoc68"><B><FONT SIZE=4>6.7.3</FONT></B></A></TD>
<TD WIDTH="100%" ALIGN=center><B><FONT SIZE=4>Operations on data structures</FONT></B></TD>
</TR></TABLE></DIV></TD>
</TR></TABLE><BR>
<TABLE CELLPADDING=0 CELLSPACING=0 WIDTH="100%">
<TR><TD BGCOLOR="#98ff98"><DIV ALIGN=center><TABLE>
<TR><TD><B>Products</B></TD>
</TR></TABLE></DIV></TD>
</TR></TABLE><BR>
The expression <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>,</FONT></TT> ... <TT><FONT COLOR=blue>,</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB> evaluates to the
<I>n</I>-tuple of the values of expressions <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> to <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB>. The
evaluation order for the subexpressions is not specified.<BR>
<BR>
<TABLE CELLPADDING=0 CELLSPACING=0 WIDTH="100%">
<TR><TD BGCOLOR="#98ff98"><DIV ALIGN=center><TABLE>
<TR><TD><B>Variants</B></TD>
</TR></TABLE></DIV></TD>
</TR></TABLE><BR>
The expression <TT><I><FONT COLOR=maroon>ncconstr</FONT></I></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> evaluates to the variant value whose
constructor is <TT><I><FONT COLOR=maroon>ncconstr</FONT></I></TT>, and whose argument is the value of <TT><I><FONT COLOR=maroon>expr</FONT></I></TT>.<BR>
<BR>
For lists, some syntactic sugar is provided. The expression
<TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>::</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> stands for the constructor <TT><FONT COLOR=blue>(</FONT></TT> <TT><FONT COLOR=blue>::</FONT></TT> <TT><FONT COLOR=blue>)</FONT></TT>
applied to the argument <TT><FONT COLOR=blue>(</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>,</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> <TT><FONT COLOR=blue>)</FONT></TT>, and therefore
evaluates to the list whose head is the value of <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> and whose tail
is the value of <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB>. The expression <TT><FONT COLOR=blue>[</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>;</FONT></TT> ... <TT><FONT COLOR=blue>;</FONT></TT>
<TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB> <TT><FONT COLOR=blue>]</FONT></TT> is equivalent to <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>::</FONT></TT> ... <TT><FONT COLOR=blue>::</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB> <TT><FONT COLOR=blue>::</FONT></TT>
<TT><FONT COLOR=blue>[]</FONT></TT>, and therefore evaluates to the list whose elements are the
values of <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> to <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB>.<BR>
<BR>
<TABLE CELLPADDING=0 CELLSPACING=0 WIDTH="100%">
<TR><TD BGCOLOR="#98ff98"><DIV ALIGN=center><TABLE>
<TR><TD><B>Polymorphic variants</B></TD>
</TR></TABLE></DIV></TD>
</TR></TABLE><BR>
The expression <TT><FONT COLOR=blue>`</FONT></TT><TT><I><FONT COLOR=maroon>tag-name</FONT></I></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> evaluates to the variant value whose
tag is <TT><I><FONT COLOR=maroon>tag-name</FONT></I></TT>, and whose argument is the value of <TT><I><FONT COLOR=maroon>expr</FONT></I></TT>.<BR>
<BR>
<TABLE CELLPADDING=0 CELLSPACING=0 WIDTH="100%">
<TR><TD BGCOLOR="#98ff98"><DIV ALIGN=center><TABLE>
<TR><TD><B>Records</B></TD>
</TR></TABLE></DIV></TD>
</TR></TABLE><BR>
The expression <TT><FONT COLOR=blue>{</FONT></TT> <TT><I><FONT COLOR=maroon>field</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>=</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>;</FONT></TT> ... <TT><FONT COLOR=blue>;</FONT></TT> <TT><I><FONT COLOR=maroon>field</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB> <TT><FONT COLOR=blue>=</FONT></TT>
<TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB> <TT><FONT COLOR=blue>}</FONT></TT> evaluates to the record value
<TT><FONT COLOR=blue>{</FONT></TT> <TT><I><FONT COLOR=maroon>field</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>=</FONT></TT> <TT><I><FONT COLOR=maroon>v</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>;</FONT></TT> ... <TT><FONT COLOR=blue>;</FONT></TT> <TT><I><FONT COLOR=maroon>field</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB> <TT><FONT COLOR=blue>=</FONT></TT> <TT><I><FONT COLOR=maroon>v</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB> <TT><FONT COLOR=blue>}</FONT></TT>,
where <TT><I><FONT COLOR=maroon>v</FONT></I></TT><SUB><FONT SIZE=2><I>i</I></FONT></SUB> is the value of <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2><I>i</I></FONT></SUB> for <I>i</I> = 1,... , <I>n</I>.
The fields <TT><I><FONT COLOR=maroon>field</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> to <TT><I><FONT COLOR=maroon>field</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB> must all belong to the same record
types; all fields belonging to this record type must appear exactly
once in the record expression, though they can appear in any
order. The order in which <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> to <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB> are evaluated is not
specified.<BR>
<BR>
The expression
<TT><FONT COLOR=blue>{</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>with</FONT></TT> <TT><I><FONT COLOR=maroon>field</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>=</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>;</FONT></TT> ... <TT><FONT COLOR=blue>;</FONT></TT> <TT><I><FONT COLOR=maroon>field</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB> <TT><FONT COLOR=blue>=</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB> <TT><FONT COLOR=blue>}</FONT></TT>
builds a fresh record with fields <TT><I><FONT COLOR=maroon>field</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> ... <TT><I><FONT COLOR=maroon>field</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB> equal to
<TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> ... <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB>, and all other fields having the same value as
in the record <TT><I><FONT COLOR=maroon>expr</FONT></I></TT>. In other terms, it returns a shallow copy of
the record <TT><I><FONT COLOR=maroon>expr</FONT></I></TT>, except for the fields <TT><I><FONT COLOR=maroon>field</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> ... <TT><I><FONT COLOR=maroon>field</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB>,
which are initialized to <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> ... <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB>.<BR>
<BR>
The expression <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>.</FONT></TT> <TT><I><FONT COLOR=maroon>field</FONT></I></TT> evaluates <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> to a record
value, and returns the value associated to <TT><I><FONT COLOR=maroon>field</FONT></I></TT> in this record
value.<BR>
<BR>
The expression <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>.</FONT></TT> <TT><I><FONT COLOR=maroon>field</FONT></I></TT> <TT><FONT COLOR=blue><-</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> evaluates <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> to a record
value, which is then modified in-place by replacing the value
associated to <TT><I><FONT COLOR=maroon>field</FONT></I></TT> in this record by the value of
<TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB>. This operation is permitted only if <TT><I><FONT COLOR=maroon>field</FONT></I></TT> has been
declared <TT><FONT COLOR=blue>mutable</FONT></TT> in the definition of the record type. The whole
expression <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>.</FONT></TT> <TT><I><FONT COLOR=maroon>field</FONT></I></TT> <TT><FONT COLOR=blue><-</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> evaluates to the unit value
<TT><FONT COLOR=blue>()</FONT></TT>.<BR>
<BR>
<TABLE CELLPADDING=0 CELLSPACING=0 WIDTH="100%">
<TR><TD BGCOLOR="#98ff98"><DIV ALIGN=center><TABLE>
<TR><TD><B>Arrays</B></TD>
</TR></TABLE></DIV></TD>
</TR></TABLE><BR>
The expression <TT><FONT COLOR=blue>[|</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>;</FONT></TT> ... <TT><FONT COLOR=blue>;</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB> <TT><FONT COLOR=blue>|]</FONT></TT> evaluates to
a <I>n</I>-element array, whose elements are initialized with the values of
<TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> to <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2><I>n</I></FONT></SUB> respectively. The order in which these
expressions are evaluated is unspecified.<BR>
<BR>
The expression <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>.(</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> <TT><FONT COLOR=blue>)</FONT></TT> returns the value of element
number <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> in the array denoted by <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB>. The first element
has number 0; the last element has number <I>n</I>-1, where <I>n</I> is the
size of the array. The exception <TT>Invalid_argument</TT> is raised if the
access is out of bounds.<BR>
<BR>
The expression <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>.(</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> <TT><FONT COLOR=blue>)</FONT></TT> <TT><FONT COLOR=blue><-</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>3</FONT></SUB> modifies in-place
the array denoted by <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB>, replacing element number <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> by
the value of <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>3</FONT></SUB>. The exception <TT>Invalid_argument</TT> is raised if
the access is out of bounds. The value of the whole expression is <TT><FONT COLOR=blue>()</FONT></TT>.<BR>
<BR>
<TABLE CELLPADDING=0 CELLSPACING=0 WIDTH="100%">
<TR><TD BGCOLOR="#98ff98"><DIV ALIGN=center><TABLE>
<TR><TD><B>Strings</B></TD>
</TR></TABLE></DIV></TD>
</TR></TABLE><BR>
The expression <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>.[</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> <TT><FONT COLOR=blue>]</FONT></TT> returns the value of character
number <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> in the string denoted by <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB>. The first character
has number 0; the last character has number <I>n</I>-1, where <I>n</I> is the
length of the string. The exception <TT>Invalid_argument</TT> is raised if the
access is out of bounds.<BR>
<BR>
The expression <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>.[</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> <TT><FONT COLOR=blue>]</FONT></TT> <TT><FONT COLOR=blue><-</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>3</FONT></SUB> modifies in-place
the string denoted by <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB>, replacing character number <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> by
the value of <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>3</FONT></SUB>. The exception <TT>Invalid_argument</TT> is raised if
the access is out of bounds. The value of the whole expression is <TT><FONT COLOR=blue>()</FONT></TT>.<BR>
<BR>
<TABLE CELLPADDING=0 CELLSPACING=0 WIDTH="100%">
<TR><TD BGCOLOR="#7fff7f"><DIV ALIGN=center><TABLE>
<TR><TD><A NAME="htoc69"><B><FONT SIZE=4>6.7.4</FONT></B></A></TD>
<TD WIDTH="100%" ALIGN=center><B><FONT SIZE=4>Operators</FONT></B></TD>
</TR></TABLE></DIV></TD>
</TR></TABLE><BR>
Symbols from the class <TT><FONT COLOR=blue>infix-symbols</FONT></TT>, as well as the keywords
<TT>*</TT>, <TT>=</TT>, <TT>or</TT> and <TT>&</TT>, can appear in infix position (between two
expressions). Symbols from the class <TT><FONT COLOR=blue>prefix-symbols</FONT></TT>
can appear in prefix position (in front of an expression).<BR>
<BR>
Infix and prefix symbols do not have a fixed meaning: they are simply
interpreted as applications of functions bound to the names
corresponding to the symbols. The expression <TT><I><FONT COLOR=maroon>prefix-symbol</FONT></I></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> is
interpreted as the application <TT><FONT COLOR=blue>(</FONT></TT> <TT><I><FONT COLOR=maroon>prefix-symbol</FONT></I></TT> <TT><FONT COLOR=blue>)</FONT></TT>
<TT><I><FONT COLOR=maroon>expr</FONT></I></TT>. Similarly, the expression <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><I><FONT COLOR=maroon>infix-symbol</FONT></I></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> is
interpreted as the application <TT><FONT COLOR=blue>(</FONT></TT> <TT><I><FONT COLOR=maroon>infix-symbol</FONT></I></TT> <TT><FONT COLOR=blue>)</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB>.<BR>
<BR>
The table below lists the symbols defined in the initial environment
and their initial meaning. (See the description of the standard
library module <TT>Pervasive</TT> in chapter <A HREF="manual034.html#c:stdlib">20</A> for more
details). Their meaning may be changed at any time using
<TT><FONT COLOR=blue>let</FONT></TT> <TT><FONT COLOR=blue>(</FONT></TT> <TT><I><FONT COLOR=maroon>infix-op</FONT></I></TT> <TT><FONT COLOR=blue>)</FONT></TT> <TT><I><FONT COLOR=maroon>name</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><I><FONT COLOR=maroon>name</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> <TT><FONT COLOR=blue>=</FONT></TT> ...<BR>
<DIV ALIGN=center><TABLE BORDER=1 CELLSPACING=0 CELLPADDING=1 WIDTH="80%">
<TR><TD ALIGN=center NOWRAP><B>Operator</B></TD>
<TD ALIGN=center NOWRAP><B>Initial meaning</B></TD>
</TR>
<TR><TD VALIGN=top ALIGN=left NOWRAP>
<TT>+</TT></TD>
<TD VALIGN=top ALIGN=left>Integer addition.</TD>
</TR>
<TR><TD VALIGN=top ALIGN=left NOWRAP><TT>-</TT> (infix)</TD>
<TD VALIGN=top ALIGN=left>Integer subtraction.</TD>
</TR>
<TR><TD VALIGN=top ALIGN=left NOWRAP><TT>-</TT> (prefix)</TD>
<TD VALIGN=top ALIGN=left>Integer negation.</TD>
</TR>
<TR><TD VALIGN=top ALIGN=left NOWRAP><TT>*</TT></TD>
<TD VALIGN=top ALIGN=left>Integer multiplication.</TD>
</TR>
<TR><TD VALIGN=top ALIGN=left NOWRAP><TT>/</TT></TD>
<TD VALIGN=top ALIGN=left>Integer division.
Raise <TT>Division_by_zero</TT> if second argument is zero. The result is
unspecified if either argument is negative.</TD>
</TR>
<TR><TD VALIGN=top ALIGN=left NOWRAP><TT>mod</TT></TD>
<TD VALIGN=top ALIGN=left>Integer modulus. Raise
<TT>Division_by_zero</TT> if second argument is zero. The result is
unspecified if either argument is negative.</TD>
</TR>
<TR><TD VALIGN=top ALIGN=left NOWRAP><TT>land</TT></TD>
<TD VALIGN=top ALIGN=left>Bitwise logical ``and'' on integers.</TD>
</TR>
<TR><TD VALIGN=top ALIGN=left NOWRAP><TT>lor</TT></TD>
<TD VALIGN=top ALIGN=left>Bitwise logical ``or'' on integers.</TD>
</TR>
<TR><TD VALIGN=top ALIGN=left NOWRAP><TT>lxor</TT></TD>
<TD VALIGN=top ALIGN=left>Bitwise logical ``exclusive or'' on integers.</TD>
</TR>
<TR><TD VALIGN=top ALIGN=left NOWRAP><TT>lsl</TT></TD>
<TD VALIGN=top ALIGN=left>Bitwise logical shift left on integers.</TD>
</TR>
<TR><TD VALIGN=top ALIGN=left NOWRAP><TT>lsr</TT></TD>
<TD VALIGN=top ALIGN=left>Bitwise logical shift right on integers.</TD>
</TR>
<TR><TD VALIGN=top ALIGN=left NOWRAP><TT>asr</TT></TD>
<TD VALIGN=top ALIGN=left>Bitwise arithmetic shift right on integers.</TD>
</TR>
<TR><TD VALIGN=top ALIGN=left NOWRAP><TT>+.</TT></TD>
<TD VALIGN=top ALIGN=left>Floating-point addition.</TD>
</TR>
<TR><TD VALIGN=top ALIGN=left NOWRAP><TT>-.</TT> (infix)</TD>
<TD VALIGN=top ALIGN=left>Floating-point subtraction.</TD>
</TR>
<TR><TD VALIGN=top ALIGN=left NOWRAP><TT>-.</TT> (prefix)</TD>
<TD VALIGN=top ALIGN=left>Floating-point negation.</TD>
</TR>
<TR><TD VALIGN=top ALIGN=left NOWRAP><TT>*.</TT></TD>
<TD VALIGN=top ALIGN=left>Floating-point multiplication.</TD>
</TR>
<TR><TD VALIGN=top ALIGN=left NOWRAP><TT>/.</TT></TD>
<TD VALIGN=top ALIGN=left>Floating-point division.</TD>
</TR>
<TR><TD VALIGN=top ALIGN=left NOWRAP><TT>**</TT></TD>
<TD VALIGN=top ALIGN=left>Floating-point exponentiation.</TD>
</TR>
<TR><TD VALIGN=top ALIGN=left NOWRAP><TT>@</TT> </TD>
<TD VALIGN=top ALIGN=left>List concatenation.</TD>
</TR>
<TR><TD VALIGN=top ALIGN=left NOWRAP><TT>^</TT> </TD>
<TD VALIGN=top ALIGN=left>String concatenation.</TD>
</TR>
<TR><TD VALIGN=top ALIGN=left NOWRAP><TT>!</TT> </TD>
<TD VALIGN=top ALIGN=left>Dereferencing (return the current
contents of a reference).</TD>
</TR>
<TR><TD VALIGN=top ALIGN=left NOWRAP><TT>:=</TT></TD>
<TD VALIGN=top ALIGN=left>Reference assignment (update the
reference given as first argument with the value of the second
argument).</TD>
</TR>
<TR><TD VALIGN=top ALIGN=left NOWRAP><TT>=</TT> </TD>
<TD VALIGN=top ALIGN=left>Structural equality test.</TD>
</TR>
<TR><TD VALIGN=top ALIGN=left NOWRAP><TT><></TT> </TD>
<TD VALIGN=top ALIGN=left>Structural inequality test.</TD>
</TR>
<TR><TD VALIGN=top ALIGN=left NOWRAP><TT>==</TT> </TD>
<TD VALIGN=top ALIGN=left>Physical equality test.</TD>
</TR>
<TR><TD VALIGN=top ALIGN=left NOWRAP><TT>!=</TT> </TD>
<TD VALIGN=top ALIGN=left>Physical inequality test.</TD>
</TR>
<TR><TD VALIGN=top ALIGN=left NOWRAP><TT><</TT> </TD>
<TD VALIGN=top ALIGN=left>Test ``less than''.</TD>
</TR>
<TR><TD VALIGN=top ALIGN=left NOWRAP><TT><=</TT> </TD>
<TD VALIGN=top ALIGN=left>Test ``less than or equal''.</TD>
</TR>
<TR><TD VALIGN=top ALIGN=left NOWRAP><TT>></TT> </TD>
<TD VALIGN=top ALIGN=left>Test ``greater than''.</TD>
</TR>
<TR><TD VALIGN=top ALIGN=left NOWRAP><TT>>=</TT> </TD>
<TD VALIGN=top ALIGN=left>Test ``greater than or equal''.</TD>
</TR></TABLE></DIV><BR>
<TABLE CELLPADDING=0 CELLSPACING=0 WIDTH="100%">
<TR><TD BGCOLOR="#7fff7f"><DIV ALIGN=center><TABLE>
<TR><TD><A NAME="htoc70"><B><FONT SIZE=4>6.7.5</FONT></B></A></TD>
<TD WIDTH="100%" ALIGN=center><B><FONT SIZE=4>Objects</FONT></B></TD>
</TR></TABLE></DIV></TD>
</TR></TABLE> <A NAME="s:objects"></A><BR>
<TABLE CELLPADDING=0 CELLSPACING=0 WIDTH="100%">
<TR><TD BGCOLOR="#98ff98"><DIV ALIGN=center><TABLE>
<TR><TD><B>Object creation</B></TD>
</TR></TABLE></DIV></TD>
</TR></TABLE><BR>
<A NAME="@manual.kwd51"></A><BR>
When <TT><I><FONT COLOR=maroon>class-path</FONT></I></TT> evaluates to a class body, <TT><FONT COLOR=blue>new</FONT></TT> <TT><I><FONT COLOR=maroon>class-path</FONT></I></TT>
evaluates to an object containing the instance variables and
methods of this class.<BR>
<BR>
When <TT><I><FONT COLOR=maroon>class-path</FONT></I></TT> evaluates to a class function, <TT><FONT COLOR=blue>new</FONT></TT> <TT><I><FONT COLOR=maroon>class-path</FONT></I></TT>
evaluates to a function expecting the same number of arguments and
returning a new object of this class.<BR>
<BR>
<TABLE CELLPADDING=0 CELLSPACING=0 WIDTH="100%">
<TR><TD BGCOLOR="#98ff98"><DIV ALIGN=center><TABLE>
<TR><TD><B>Message sending</B></TD>
</TR></TABLE></DIV></TD>
</TR></TABLE><BR>
The expression <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>#</FONT></TT> <TT><I><FONT COLOR=maroon>method-name</FONT></I></TT> invokes the method
<TT><I><FONT COLOR=maroon>method-name</FONT></I></TT> of the object denoted by <TT><I><FONT COLOR=maroon>expr</FONT></I></TT>.<BR>
<BR>
If <TT><I><FONT COLOR=maroon>method-name</FONT></I></TT> is a polymorphic method, its type should be known at
the invocation site. This is true for instance if <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> is the name
of a fresh object (<TT><FONT COLOR=blue>let</FONT></TT> <TT><I><FONT COLOR=maroon>ident</FONT></I></TT> = <TT><FONT COLOR=blue>new</FONT></TT> <TT><I><FONT COLOR=maroon>class-path</FONT></I></TT> ... ) or if
there is a type constraint. Principality of the derivation can be
checked in the <TT>-principal</TT> mode.<BR>
<BR>
<TABLE CELLPADDING=0 CELLSPACING=0 WIDTH="100%">
<TR><TD BGCOLOR="#98ff98"><DIV ALIGN=center><TABLE>
<TR><TD><B>Coercion</B></TD>
</TR></TABLE></DIV></TD>
</TR></TABLE><BR>
The type of an object can be coerced (weakened) to a supertype.
The expression <TT><FONT COLOR=blue>(</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>:></FONT></TT> <TT><I><FONT COLOR=maroon>typexpr</FONT></I></TT> <TT><FONT COLOR=blue>)</FONT></TT> coerces the expression <TT><I><FONT COLOR=maroon>expr</FONT></I></TT>
to type <TT><I><FONT COLOR=maroon>typexpr</FONT></I></TT>.
The expression <TT><FONT COLOR=blue>(</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> <TT><FONT COLOR=blue>:</FONT></TT> <TT><I><FONT COLOR=maroon>typexpr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> <TT><FONT COLOR=blue>:></FONT></TT> <TT><I><FONT COLOR=maroon>typexpr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> <TT><FONT COLOR=blue>)</FONT></TT> coerces the
expression <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> from type <TT><I><FONT COLOR=maroon>typexpr</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> to type <TT><I><FONT COLOR=maroon>typexpr</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB>.
The former operator will sometimes fail to coerce an expression <TT><I><FONT COLOR=maroon>expr</FONT></I></TT>
from a type <TT><I><FONT COLOR=maroon>t</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> to a type <TT><I><FONT COLOR=maroon>t</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB> even if type <TT><I><FONT COLOR=maroon>t</FONT></I></TT><SUB><FONT SIZE=2>1</FONT></SUB> is a subtype of type
<TT><I><FONT COLOR=maroon>t</FONT></I></TT><SUB><FONT SIZE=2>2</FONT></SUB>: in the current implementation it only expands two levels of
type abbreviations containing objects and/or variants, keeping only
recursion when it is explicit in the class type. In case of failure,
the latter operator should be used.<BR>
<BR>
In a class definition, coercion to the type this class defines is the
identity, as this type abbreviation is not yet completely defined.<BR>
<BR>
<TABLE CELLPADDING=0 CELLSPACING=0 WIDTH="100%">
<TR><TD BGCOLOR="#98ff98"><DIV ALIGN=center><TABLE>
<TR><TD><B>Object duplication</B></TD>
</TR></TABLE></DIV></TD>
</TR></TABLE><BR>
An object can be duplicated using the library function <TT>Oo.copy</TT>
(see
<a HREF=libref/Oo.html>Module <tt>Oo</tt></a>
). Inside a method, the expression
<TT><FONT COLOR=blue>{<</FONT></TT> <TT><I><FONT COLOR=maroon>inst-var-name</FONT></I></TT> <TT><FONT COLOR=blue>=</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> { <TT><FONT COLOR=blue>;</FONT></TT> <TT><I><FONT COLOR=maroon>inst-var-name</FONT></I></TT> <TT><FONT COLOR=blue>=</FONT></TT> <TT><I><FONT COLOR=maroon>expr</FONT></I></TT> } <TT><FONT COLOR=blue>>}</FONT></TT>
returns a copy of self with the given instance variables replaced by
the values of the associated expressions; other instance variables
have the same value in the returned object as in self.<BR>
<BR>
<BR>
<BR>
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