Re: Bug? Or at least a better error message?

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.