30 May
2009
30 May
'09
5:37 p.m.
michael rice
The following code is from Section 8.4.2, pgs. 111-112 (PDF paging) of YAHT. It compiles fine, but upon trying it I get the following error message. It seems to be trying to 'Show' the Computation class but I'm not sure where to put the 'Deriving'.
My guess is that your expression is polymorphic, returning Computation c => c [Int] Since Haskell knows how to show this for both of the instances defined for Computation (i.e. Maybe [Int] and [[Int]]), perhaps you could give one of those as an explicit type signature? -k -- If I haven't seen further, it is by standing in the footprints of giants