runtime(haskell): allow spaces in backticked operators in syntax script

This formatting (although rare) is actually accepted by GHC, but vim
does not highlight it. This patch adds the simplest possible regex to
support the behavior.

Inconveniently, this might trigger weird formatting on lines that
contain errors, e.g. if the first backtick is removed from:

    a `b` c `d` e

then `c` is going to be marked as an operator, which seems weird but is
valid.

closes: #18776

Signed-off-by: Mirek Kratochvil <exa.exa@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

diff --git a/runtime/syntax/haskell.vim b/runtime/syntax/haskell.vim
index 509aa25122a7b88b73cc115bf5c89b4ba36459d3..e71e1c8072ae89ecc2674fbb378ad21b9f1f7c1c 100644 (file)
--- a/runtime/syntax/haskell.vim
+++ b/runtime/syntax/haskell.vim
@@ -2,6 +2,7 @@
 " Language:            Haskell
 " Maintainer:          Haskell Cafe mailinglist <haskell-cafe@haskell.org>
 " Last Change:         2024 Mar 28 by Enrico Maria De Angelis <enricomaria.dean6elis@gmail.com>
+"                      2025 Nov 20 by Vim Project: Allow spaces in backticks #18776
 " Original Author:     John Williams <jrw@pobox.com>
 "
 " Thanks to Ryan Crumley for suggestions and John Meacham for
@@ -46,8 +47,8 @@ syn match VarId "\(\<[A-Z][a-zA-Z0-9_']*\.\)*\<[a-z][a-zA-Z0-9_']*\>" contains=@
 " others are variables (e.g. functions).
 syn match hsVarSym "\(\<[A-Z][a-zA-Z0-9_']*\.\)\=[-!#$%&\*\+/<=>\?@\\^|~.][-!#$%&\*\+/<=>\?@\\^|~:.]*"
 syn match hsConSym "\(\<[A-Z][a-zA-Z0-9_']*\.\)\=:[-!#$%&\*\+./<=>\?@\\^|~:]*"
-syn match hsVarSym "`\(\<[A-Z][a-zA-Z0-9_']*\.\)\=[a-z][a-zA-Z0-9_']*`"
-syn match hsConSym "`\(\<[A-Z][a-zA-Z0-9_']*\.\)\=[A-Z][a-zA-Z0-9_']*`"
+syn match hsVarSym "` *\(\<[A-Z][a-zA-Z0-9_']*\.\)\=[a-z][a-zA-Z0-9_']* *`"
+syn match hsConSym "` *\(\<[A-Z][a-zA-Z0-9_']*\.\)\=[A-Z][a-zA-Z0-9_']* *`"
 
 " (Non-qualified) identifiers which start with # are labels
 syn match hsLabel "#[a-z][a-zA-Z0-9_']*\>"