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Today's Topics:
1. Non type-variable argument (Nikolay Kurtov)
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Message: 1
Date: Wed, 14 Jun 2017 20:52:32 +0200
From: Nikolay Kurtov <nkur...@gmail.com>
To: beginners@haskell.org
Subject: [Haskell-beginners] Non type-variable argument
Message-ID:
<cag+yhsn+06cm4vx3nur68o8wftbh-wycnsq0_ce+eknz33f...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
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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