#3919: Or-patterns as GHC extension
---------------------------------+------------------------------------------
Reporter: BjornEdstrom | Owner:
Type: feature request | Status: new
Priority: normal | Component: Compiler
Version: | Keywords:
Os: Unknown/Multiple | Testcase:
Architecture: Unknown/Multiple | Failure: None/Unknown
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Or-patterns is a way of grouping together patterns that match to the same
value. A construct like
{{{
fun 0 _ = E
fun _ 0 = E
}}}
Could more concisely be written as, for example
{{{
fun 0 _
|| _ 0 = E
}}}
As a concrete example why this is beautiful and how it could look, see
''Red-black trees in a functional setting, C. Okasaki'' [1].
I don't know enough about GHC internals to know the obvious way to
implement this, but I would gladly give it a try given pointers in the
right direction.
[1] http://www.eecs.usma.edu/webs/people/okasaki/jfp99.ps
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3919>
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