Standard (core) libraries initiative: rationale

Simon Marlow simonmarhaskell at
Tue Nov 28 06:48:16 EST 2006

David Roundy wrote:
> On Mon, Nov 27, 2006 at 10:28:09PM +0300, Bulat Ziganshin wrote:
>>and this leads us to other question - whether this set and API of each
>>library should be fixed in language standard or it can evolve during
>>the time?...
> To me, this is the deciding issue.  The Haskell 98 libraries have some
> severe issues which are unfixable because they're defined as part of the
> standard.  My preference for Haskell' would be to have a *reduction* in the
> size of the core libraries.  For example, the Time and Locale modules are
> pretty much useless, and totally unnecessary, since they can be easily
> implemented in Haskell 98.
> Yes, it would be nice to have at least a de facto standard set of
> libraries, but this is best done apart from the language standardization
> process.  This has worked reasonably well so far, and has mostly been
> hampered by the limitations of Haskell 98, which mean that relatively few
> libraries support the standard Haskell language.  I'd like to see work on a
> standard set of libraries follow Haskell', with the libraries being written
> in pure Haskell'.  The libraries defined in the standard should be limited
> to those which are either universally used or necesary in order to
> implement the rest of the libraries.

This pretty much echoes my thoughts on the issue too.  And we've talked about it 
in the context of Haskell': the current plan is to do exactly what you suggest 
and have only a very minimal set of libraries standardised as part of the 
Haskell' language.  On top of this will be a much larger set of standard 
libraries, but these will be standardised by a process (and committee) separate 
from the Haskell' committee.  There was a general concensus amongst the Haskell' 
committee for this approach.

It might make sense for the current "Core Libraries" proposal to coincide with 
the Haskell' standard libraries process, but I imagine the latter will subject 
every library to a lot more scrutiny and hence will take a lot longer.  In the 
meantime, we want something cheap and useful, which is what "Core Libraries" 
should be.


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