#4316: Interactive "do" notation in GHCi
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Reporter: mitar | Owner: vivian
Type: feature request | Status: patch
Priority: normal | Milestone: 7.2.1
Component: GHCi | Version: 6.12.3
Keywords: | Testcase:
Blockedby: | Difficulty:
Os: Unknown/Multiple | Blocking:
Architecture: Unknown/Multiple | Failure: None/Unknown
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Comment(by vivian):
Replying to [comment:12 simonmar]:
> Just a thought: couldn't we use the "altnerative layout rule" to detect
when a line ends without closing all of its layout contexts, and enter a
multi-line mode which ends with a blank line, or when all the layout
contexts have been closed?
I do not know how to 'hook' into the lexer to check whether a layout rule
is open. {{{Lexer.x, lexer}}}, about line 1961, is where layout is
implemented.
A statement "let foo = bar" is a valid expression at the GHCi command
line, but could also be an open layout context expecting "in baz foo" to
close the context on the next line.
A trailing {{{do}}} on the command line generates an "Empty 'do'
construct" error, not an error about layout, which is why I can not see
(yet) how to get the layout context information from the parser.
Perhaps simonmar could provide me with a pointer as to how to implement
his suggestion?
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4316#comment:13>
GHC <http://www.haskell.org/ghc/>
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