5 Jun
2006
5 Jun
'06
12:57 p.m.
Geoffrey Alan Washburn wrote:
Brian Hulley wrote:
I must admit I can't understand where the ambiguity actually is. bar has been defined as a -> Int, so surely anything on the rhs of an equation for an instance of the bar method in Foo is therefore an Int also, so having to explicitly write 1::Int seems superfluous.
bar([x]) = 1 -- why is ::Int needed when we know that bar:: a->Int ???
I haven't tested the combination where I omit the annotation on "bar([x]) = 1", but I believe that the annotation is only actualyl necessary for the "bar [] = bar [1]" case where ghc cannot determine the type at which it needs to be calling bar recursively.
Oh I see now - I was looking at the wrong "1" ! :-) Thanks, Brian.