MODULE

	lfe_macro

MODULE SUMMARY

	Lisp Flavoured Erlang (LFE) macro expander

DESCRIPTION

	This module provides an interface to the LFE macro expander.
	The expander is used by the LFE compile and in the shell but
	can also be used by applications explicitly wanting to handle
	a file.

DATA TYPES

	sexpr()
		An LFE s-expression, a list structure.
	filesexpr() = {Sexpr,Line}
		This is the format returned by lfe_io:parse_file/1 and
		is used by the compiler to give better error
		information.
     	env()
		This is an macro and evaluation environment as created
		by lfe_lib:new_env().

EXPORTS

expand_form(Sexpr) -> Sexpr.
expand_form(Sexpr, Env) -> Sexpr.

	where
	  Sexpr = sexpr()
	  Env = env()

	Expand all macros in Sexpr either using the definitions in Env
	or jst the default macros. Note that any eventual new macro
	definitions will be lost.

expand_forms([FileSexpr]) -> [FileSexpr].
expand_forms([FileSexpr], Env) -> {[FileSexpr],Env}.

	where
	  FileSexpr = filesexpr()
	  Env = env()

macro_forms([FileSexpr], Env) -> {[FileSexpr],Env}.

	where
	  FileSexpr = filesexpr()
	  Env = env()

expand_macro(Sexpr, Env) -> {yes,Exp} | no.
expand_macro_1(Sexpr, Env) -> {yes,Exp} | no.

	where
	  Sexpr = Exp = sexpr()
	  Env = env()

	Test if the top s-expression here is a macro call, if so
	expand it and return {yes,Expansion}, if not then return no.
	expand_macro/2 will expand the top s-expression as much as
	possible while expand_macro_1/2 will only try it once. These
	functions use the macro definitions in the environment and the
	standard pre-defined macros.