[Haskell-cafe] Names in a record changes read behavior?

Brandon Allbery allbery.b at gmail.com
Mon Jul 27 20:56:29 UTC 2015


On Mon, Jul 27, 2015 at 4:25 PM, Mike Meyer <mwm at mired.org> wrote:

> OK, why won't read accept the same syntax as the REPL? I can see wanting
> Read and Show to be inverses of each other, though I think it's a bit
> misguided. But if we're going to be that strict about them being inverses,
> shouldn't we also insist that the READ eval print loop only accept what
> read will accept?


Partly because ReadS isn't a very good parser, partly because of compliance
with
https://www.haskell.org/onlinereport/haskell2010/haskellch11.html#x18-18600011.4;
notably:

   - If the constructor is defined using record syntax, the derived Read will
   parse only the record-syntax form, and furthermore, the fields must be
   given in the same order as the original declaration.

-- 
brandon s allbery kf8nh                               sine nomine associates
allbery.b at gmail.com                                  ballbery at sinenomine.net
unix, openafs, kerberos, infrastructure, xmonad        http://sinenomine.net
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