Re: [Haskell-cafe] Spot the difference!

G'day all. Quoting PR Stanley :

\_ n -> 1 + n \_ -> (\n -> 1 + n) The outcome seems to be identical. is there a substantive difference between the two definitions?

Certainly, GHC compiles these to the same code. But be careful! Consider the following two defintions: test1 n _ = 1 + n test2 n = \_ -> 1 + n I don't know if it's still the case, but GHC used to compile different code for these at high optimisation levels. The first was essentially compiled to: test1 = \n _ -> 1+n And the second to: test2 = \n -> let x = n+1 in \_ -> x The difference is that test1 is faster if it's usually fully applied, test2 is fully lazy. Cheers, Andrew Bromage