#4370: Bring back monad comprehensions
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Reporter: simonpj | Owner: nsch
Type: feature request | Status: new
Priority: normal | Milestone: 7.2.1
Component: Compiler | Version: 6.12.3
Keywords: | Testcase:
Blockedby: | Difficulty:
Os: Unknown/Multiple | Blocking:
Architecture: Unknown/Multiple | Failure: None/Unknown
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Comment(by simonpj):
I've just got rid of that `SyntaxTable` on `MDoExpr`. As discussed above,
it's a relic, and getting rid of it tidied up the code quite a bit.
You'll want to pull the patch before recording yours
{{{
Wed Dec 22 05:22:10 PST 2010 [email protected]
* Tidy up rebindable syntax for MDo
For a long time an 'mdo' expression has had a SyntaxTable
attached to it. However, we're busy deprecating SyntaxTables
in favour of rebindable syntax attached to individual Stmts,
and MDoExpr was totally inconsistent with DoExpr in this
regard.
This patch tidies it all up. Now there's no SyntaxTable on
MDoExpr, and 'modo' is generally handled much more like 'do'.
There is resulting small change in behaviour: now MonadFix is
required only if you actually *use* recursion in mdo. This
seems consistent with the implicit dependency analysis that
is done for mdo.
Still to do:
* Deal with #4148 (this patch is on the way)
* Get rid of the last remaining SyntaxTable on HsCmdTop
M ./compiler/deSugar/Coverage.lhs -6 +1
M ./compiler/deSugar/DsArrows.lhs -2 +2
M ./compiler/deSugar/DsExpr.lhs -36 +32
M ./compiler/hsSyn/HsExpr.lhs -12 +7
M ./compiler/hsSyn/HsUtils.lhs -1 +1
M ./compiler/parser/Parser.y.pp -1 +3
M ./compiler/rename/RnBinds.lhs -1 +1
M ./compiler/rename/RnExpr.lhs -39 +15
M ./compiler/rename/RnExpr.lhs-boot -1 +1
M ./compiler/typecheck/TcHsSyn.lhs -14 +4
M ./compiler/typecheck/TcMatches.lhs -21 +7
M ./compiler/typecheck/TcRnDriver.lhs -1 +2
}}}
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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4370#comment:21>
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