21 Mar
2008
21 Mar
'08
6:18 a.m.
On Thu, 20 Mar 2008, Roberto Zunino wrote:
ac wrote:
foo :: [Foo] ->
foo xs = map xs What are the possible type signatures for placeholder 1 and the possible expressions for placeholder 2?
A nice GHCi trick I learned from #haskell:
:t let foo xs = map ?placeholder2 xs in foo
forall a b. (?placeholder2::a -> b) => [a] -> [b]
Also, the djinn tool might provide some actual expression for placeholder 2.
http://www.haskell.org/haskellwiki/Determining_the_type_of_an_expression