Proposal #3339: Add (+>) as a synonym for mappend

Simon Peyton-Jones simonpj at
Mon Nov 7 11:14:29 CET 2011

| >>    ptext (sLit "In module")
| >> <+> quotes (ppr (is_mod decl_spec))
| >> <+> source_import <> colon
| >
| > BTW, I should note that it looks like this is the only instance of this
| > problem in the whole of ghc
| So let's just fix ghc here.  It looks to me like whoever wrote that code was relying
| on a non-obvious consequence of the precedence.  At a glance, it looks like there is
| intended to be a space before the source_import and colon.  And that is exactly what
| the proposed fixities for <> and <+> will give.  I find it hard to believe that many
| people would consciously have relied on the older behaviour.

If there's a bug in GHC, or a feature request, can someone make a ticket with a standalone reproducible test case, please? I have not been following the twists and turns of this discussion.


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