definition module ast

:: AST = AST [Function]

:: Function = Function String [String] Expression

:: Expression
	= Literal Value
	| Variable String
	| Apply Expression Expression
	| Lambda String Expression
	| Let String Expression Expression
	| Code String
	| ..

:: Value
	= Int Int
	| Bool Bool
	| Char Char

instance toString AST
instance toString Function
instance toString Expression
instance toString Value