On Sun, Feb 20, 2011 at 10:20 PM, Max Bolingbroke <[email protected]> wrote: > On 20 February 2011 19:56, Mihai Maruseac <[email protected]> wrote: >> Hi, >> >> When running Alex -g I get several warning telling me that a bang >> pattern is required and that the warning will be an error in GHC 6.14. > > As it happens, that is not an error in GHC 7 (see > http://hackage.haskell.org/trac/ghc/ticket/3278): > > """ > $ ghci -XMagicHash > GHCi, version 7.0.1.20101215: http://www.haskell.org/ghc/ :? for help > letLoading package ghc-prim ... linking ... done. > Loading package integer-gmp ... linking ... done. > Loading package base ... linking ... xdone. > Loading package ffi-1.0 ... linking ... done. > Prelude> let x = 2# in 10 > > <interactive>:1:5: > Warning: Bindings containing unlifted types should use an > outermost bang pattern: > x = 2# > In the expression: let x = 2# in 10 > In an equation for `it': it = let x = 2# in 10 > > <interactive>:1:5: > Warning: Bindings containing unlifted types should use an > outermost bang pattern: > x = 2# > In the expression: let x = 2# in 10 > In an equation for `it': it = let x = 2# in 10 > 10 > """ > > (I'm not quite sure why I get two identical warnings..) > > It looks like Alex has gone back and forth on what to do here. Selected > commits: > > """ > Fri Nov 26 10:43:42 GMT 2010 Simon Marlow <[email protected]> > * don't use CPP for LANGUAGE pragmas > Drop the -fno-warn-lazy-unlifted-bindings again. CPP in the header > prevents the user from adding their own LANGUAGE pragmas at the top of > the .x file if they're using GHC < 7.0. > > Wed Nov 17 10:42:23 GMT 2010 Simon Marlow <[email protected]> > * Stop using -fglasgow-exts, and turn off bogus bang-pattern warnings > > Wed Nov 17 10:41:06 GMT 2010 Simon Marlow <[email protected]> > * remove bang patterns on unlifted bindings again > > Wed Jun 3 23:58:54 BST 2009 Ian Lynagh <[email protected]> > * Use bang patterns on unlifted bindings > """ > > So it looks like you should just ignore this warning, or turn it off :-) >
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