#2798: Enable "rec" keyword when RecursiveDo is enabled?
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Reporter: nominolo | Owner:
Type: task | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 6.11
Severity: minor | Resolution:
Keywords: | Difficulty: Unknown
Testcase: | Architecture: Unknown/Multiple
Os: Unknown/Multiple |
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Comment (by claus):
Replying to [comment:2 simonpj]:
> I think the reason for 'mdo' was by analogy with 'let' and 'where': just
say "use recursion" and let the compiler sort out the details.
I have often wanted a non-recursive 'let' as well as the current 'let
rec'. It would get rid of many unreadable '-ed names and silly bugs. 'do',
with non-recursive bindings by default, and recursive bindings possible,
is slightly more pleasant in this regard (though the syntactic differences
between pure and monadic bindings are too awkward). Unfortunately, that
nice and simple distinction is out of reach for 'let' (too much code out
there), but "let the compiler sort out the details" is good only if
programmers still have control, and renaming is not the nicest way of
exercising such control.
> * Remove 'mdo' and use 'do rec' instead
Without bias to the actual choice, the name 'mdo' is unfortunate - I doubt
it makes sense to Haskell newcomers, nor does it evoke useful semantic
associations.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2798#comment:3>
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