when giving an error "No instance for C (a -> b)", suggest that a function may be underapplied (#9613) · Issues · Glasgow Haskell Compiler / GHC

when giving an error "No instance for C (a -> b)", suggest that a function may be underapplied

Suggestion of ibotty here: http://www.reddit.com/r/haskell/comments/2go92u/beginner_error_messages_in_c_vs_haskell/cklm7jk

Prelude> print length

<interactive>:2:1:
    No instance for (Show ([a0] -> Int)) arising from a use of ‘print’
        but there is an instance for (Show Int);
        maybe you omitted an argument to ‘length’ of type [a0]?
    In the expression: print length
    In an equation for ‘it’: it = print length

I guess the trickiest part will be figuring out what function is underapplied.

Trac metadata

Trac field	Value
Version	7.8.3
Type	FeatureRequest
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler (Type checker)
Test case
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