definition module ast

from Data.Either import :: Either
from StdOverloaded import class toString

from int import :: Eval

:: Function = Function [Char] [[Char]] Expression

:: Expression
	= Lit Value
	| Var [Char]
	| App Expression Expression
	| Lambda [Char] Expression
	| Let [([Char], Expression)] Expression

:: Value
	= Int Int
	| Bool Bool
	| Lambda` [Char] Expression
	| Builtin (Expression -> Eval Expression)

instance toString Function, Expression, Value