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Excessive parser backtracking in lambda arguments #3262
Description
http://try.purescript.org/?backend=core&gist=40b83a8631b49dfb1cc7584aaea0fb1d
module Main where
import Prelude
foo = id \a ->
let
bar =
let
baz =
{ a: 42, -- Extra comma
, b: 12
}
in baz
in bar Unable to parse module:
unexpected ->
expecting indentation at column 1 or end of input
If you remove id then there is a sensible error position.
Activity
paf31 commentedon Mar 1, 2018
A smaller example:
natefaubion commentedon Mar 1, 2018
\is a valid operator, so maybe since the lambda body parse failed, it's backtracking to parseid \ a. I think since the lambda head is correct, it should be able to commit, since->is not a valid operator.natefaubion commentedon Aug 8, 2018
I think this is anything that causes backtracking to
Parsec.buildExpressionParser.bad = id [,]This example should clearly fail with an unexpected
,instead, which you'd get if you left off theid.hdgarrood commentedon Feb 14, 2019
Shall we close this in favour of #3517?
hdgarrood commentedon May 8, 2019
I think this is safe to close unless we want to add tests for error positions, but that might be more effort than it's worth.