Malcolm Wallace
Errm, you mean: 4 `Then` 5 `Then` 1 `Then` Finally "success!"
Yes, sorry, and thanks. I guess I should learn to check with ghci before posting... How about this for a nicer syntax? infixr 8 :+ infixr 8 +: data TList a e = a :+ (TList a e) | Return e deriving Show x +: y = x :+ (Return y) *Main> 2 :+ 4 +: "success" 2 :+ (4 :+ Return "success") I like the generic terminal value, it allows things like: *Main> let count = go 0 where go i (x:xs) = x :+ go (i+1) xs; go i [] = Return i *Main> :t count count :: [t] -> TList t Integer *Main> count [1..5] 1 :+ (2 :+ (3 :+ (4 :+ (5 :+ Return 5)))) (But perhaps these things can be done more elegantly using State or similar?) -k -- If I haven't seen further, it is by standing in the footprints of giants