#4148: improve new recursive do syntax
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Reporter: guest | Owner:
Type: feature request | Status: new
Priority: low | Milestone: 7.6.1
Component: Compiler | Version: 6.12.3
Keywords: | Os: Unknown/Multiple
Architecture: Unknown/Multiple | Failure: None/Unknown
Difficulty: Unknown | Testcase:
Blockedby: | Blocking:
Related: |
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Comment(by lerkok):
Ross: Strictly speaking, we don't really even need `rec`. Without
segmentation, the job of `rec` is so straightforward, I don't think asking
people to call `mfix` directly would be a big stretch. Maybe we should do
away with the whole thing.
Termination is a big issue, and there's a theorem that says segmentation
will always improve termination properties. More importantly, I do believe
it reflects the user intention better: Two sub-recursive computations
shouldn't impact each other provided they don't share any variables.
Segmentation guarantees that. Without segmentation, you get unintended
interference.
However, to put things in perspective, removal of `mdo` isn't really going
to impact a lot of folks. Those who need it can clearly work around the
issues. So, maybe Ross has the right wisdom in suggesting to go with
maximal simplicity. In that case, I'd say we should remove `rec` as well;
as it adds very little to the whole story.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4148#comment:18>
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