Haskell Platform proposal: Add case-insensitive and Haskell 98/2010 compliance

Bas van Dijk v.dijk.bas at gmail.com
Mon Jan 14 20:24:53 CET 2013

On 14 January 2013 18:20, Henning Thielemann
<lemming at henning-thielemann.de> wrote:
> On Mon, 14 Jan 2013, Ben Millwood wrote:
>> In response to this, I ask you: is compatibility with the platform really
>> a goal for your live-sequencer? Would the live-sequencer benefit
>> particularly from use of the case-insensitive package? Would making the
>> case-insensitive package Haskell2010 enable it to work with your interpreter
>> immediately?
>  My answer is no, and I think it is the wrong question. My point was, that
> case-insensitive can easily be made both Haskell98/2010 and thus improve -
> the same way the "split" package improved by removing the GADT when it was
> added to the platform.
>  I had actual problems when trying to do something sensible with JHC. It
> meant that I had to inspect and "fix" a lot of packages at once before
> seeing anything running. Not very encouraging when you try a different
> compiler.
>  FlexibleInstances are not necessary for defining instances on Strings and
> if a package enters the platform it is a good opportunity to fix that.
> Platform packages also play a role as packages where beginners look first
> when they want to learn how to program real-world Haskell.

I dropped the UnicodeSyntax, TypeSynonymInstances and
FlexibleInstances language extensions in the "hp" branch:


I added a _hidden_ foldCaseList method to the FoldCase class which is
used to case fold Strings.

A FoldCase instance for Char is added.

I dropped the FoldCase ShowS instance.

I bumped the version from to 1.0.

>> That all said, I do have my own concerns with case-insensitive.
>> Particularly, it provides an instance FoldCase ByteString, implicitly
>> treating ByteStrings as text, which I believe should be discouraged.

I agree with Gregory that the primary use case of this package was to
do case insensitive comparisons of HTTP headers in snap and yesod
which use ByteStrings to represent the headers.

I do remember there was an ascii package a while back:


Michael: what was the reason for deprecating that package?

Something else: according to the HP procedure proposals should be
discussed on the libraries list. Gregory: could you start a new
discussion there?



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