Joel Costigliola joel-costigliola

vertexcite / eval.hs

Created April 28, 2015 05:26

Monad example: simple expression evaluation - for Auckland FP Meetup 2015-04-28. By Steve Reeves

	---Very simple evaluation for arithmetic expressions with only constants
	---(and only "plus"...obviously extendable to other operations)

	data Expr = C Float \|
	Expr :+ Expr
	deriving Show

	eval :: Expr -> Float
	eval (C x) = x
	eval (e1 :+ e2) = let v1 = eval e1