Redundant constraints

Simon Peyton Jones simonpj at microsoft.com
Thu Jan 8 23:14:40 UTC 2015


I was wrong about binary, sorry.   It was just the other three

Simon

From: Lennart Kolmodin [mailto:kolmodin at gmail.com]
Sent: 08 January 2015 20:26
To: Simon Peyton Jones
Cc: ghc-devs at haskell.org; Milan Straka; Bill Mitchell (Bill.Mitchell at hq.bcs.org.uk); Judah Jacobson; Ross Paterson
Subject: Re: Redundant constraints



2015-01-07 18:19 GMT+03:00 Simon Peyton Jones <simonpj at microsoft.com<mailto:simonpj at microsoft.com>>:
Friends
I’ve pushed a big patch that adds –fwarn-redundant-constraints (on by default).  It tells you when a constraint in a signature is unnecessary, e.g.
     f :: Ord a => a -> a -> Bool
     f x y = True
I think I have done all the necessary library updates etc, so everything should build fine.
Four libraries which we don’t maintain have such warnings (MANY of them in transformers) so I’m ccing the maintainers:

o   containers

o   haskeline

o   transformers

o   binary

I'd like to update binary to not have any unnecessary constraints. I couldn't find any though.
commit c409b6f30373535b6eed92e55d4695688d32be9e removes unnecessary constraints from ghc maintained libraries, and silences the redundant-constraints warnings from the other libraries containers, haskeline and transformers.
I couldn't find anything related to binary though, nor any warnings in the build log.
If there are any, please let me know, or file a bug at http://github.com/kolmodin/binary

Thanks! Lennart


Enjoy!



Simon

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