Unknown option -XPatternSig used in warning

Bas van Dijk v.dijk.bas at gmail.com
Wed Sep 19 08:20:19 EDT 2007


$ ghc --version
The Glorious Glasgow Haskell Compilation System, version 6.7.20070915

When loading the following incorrect program in ghci:

foo (x :: a) = x

ghci rightly complains:

Illegal signature in pattern: a
	Use -XPatternSigs to permit it

OK so I follow the advice and load:

{-# OPTIONS_GHC -XPatternSigs #-}

foo (x :: a) = x

Now ghci complains:

unknown flags in  {-# OPTIONS #-} pragma: -XPatternSigs     ???

The following works though:

{-# OPTIONS_GHC -fglasgow-exts #-}

foo (x :: a) = x

results in:

 A pattern type signature cannot bind scoped type variables `a'
      unless the pattern has a rigid type context
    In the pattern: x :: a
    In the definition of `foo': foo (x :: a) = x

Which I expect.

Should I file a bug report, or is there an easy fix?


Bas van Dijk

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