[Haskell-beginners] Non type-variable argument

[Nikolay Kurtov]

Hello everyone,

Please help me compile the program without the -XFlexibleContexts extension.
I don't understand the "Non type-variable argument" error message and
googling does not shed any light on the problem.
Any help is appreciated.

% ghc --version
The Glorious Glasgow Haskell Compilation System, version 7.10.3

% ghc orfest.hs
orfest.hs:6:1:
    Non type-variable argument
      in the constraint: AM.MArray a (t, t, t, [i]) m
    (Use FlexibleContexts to permit this)
    When checking that ‘go’ has the inferred type
      go :: forall (m :: * -> *) t t1 t2 t3 (a :: * -> * -> *) i.
            (Read t, AM.Ix i, AM.MArray a (t, t1, t2, [i]) m) =>
            a i (t, t1, t2, [i]) -> [[Char]] -> t3 -> i -> m (t3, i)

This works:
% ghc orfest.hs -XFlexibleContexts

Regards,
Orfest
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