#1662: mistranslation of arrow notation
-------------------------+--------------------------------------------------
Reporter: ross | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 6.6.1
Severity: normal | Resolution:
Keywords: | Difficulty: Unknown
Os: Unknown | Testcase: arrowrun004
Architecture: Unknown |
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Comment (by ross):
The source program
{{{
expr = proc () -> do
x <- term -< ()
expr' -< x
}}}
is translated by the type checker to (simplified a bit):
{{{
expr = proc
(){(w) d 70} { arr{v aEB} [lid] = arr{v 01V} [gid]
@ (<nt>BTParser{tc rdM} ESym{tc
rdD})
$dArrow{v aEE} [lid]
$dArrow{v aEE} [lid] = $f4{v rqS} [lid] @ ESym{tc rdD}
>>>{v aEC} [lid] = (>>>{v 01W} [gid])
@ (<nt>BTParser{tc rdM} ESym{tc
rdD})
$dArrow{v aEF} [lid]
$dArrow{v aEF} [lid] = $dArrow{v aEE} [lid]
first{v aED} [lid] = first{v 01X} [gid]
@ (<nt>BTParser{tc rdM} ESym{tc
rdD})
$dArrow{v aEG} [lid]
$dArrow{v aEG} [lid] = $dArrow{v aEE} [lid] }
->
do ((x{v aeB} [lid] :: Int{(w) tc 3J})) <-
term{v rdq} [lid] -< (){(w) v 71} [gid]
expr'{v rdo} [lid] -< x{v aeB} [lid]
}}}
These bindings ought not to be attached to the pattern of `proc`, because
the scope of ''pat'' in `proc` ''pat'' `->` ''cmd'' is not the whole of
''cmd'' but only the subexpressions that are fed into arrows. The
bindings should be placed outside the `proc` expression, so that they
scope over the whole thing.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/1662>
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