[Haskell] string type class

Peter Verswyvelen bf3 at telenet.be
Fri Mar 6 14:44:24 EST 2009

What about AString or AnyString?

> -----Original Message-----
> From: haskell-bounces at haskell.org [mailto:haskell-bounces at haskell.org]
> On Behalf Of Chris Kuklewicz
> Sent: Friday, March 06, 2009 8:17 PM
> To: Matthew Pocock
> Cc: haskell at haskell.org
> Subject: Re: [Haskell] string type class
> Matthew Pocock wrote:
> > It seems every time I look at hackage there is yet another stringy
> > datatype. For lots of apps, the particular stringy datatype you use
> > matters for performance but not algorithmic reasons. Perhaps this is
> a
> > good time for someone to propose a stringy class?
> Not likely.
> I did define my own (private) class for regular expressions, to
> abstract over
> String, the ByteStrings, and Seq Char.  But it is used in one place and
> is a
> wart that should be removed.
> The simple task of looping over the contents of a String (once,
> forward) is
> quite different from a Strict ByteString (using an index and a lookup).
> This means for decent efficiency I need two copies of my code, hand
> specialized
> to each case.
> "tail" or "(x:xs)" : very efficient for String (no allocation)
> "tail" or "uncons" : not efficient for ByteString (allocation, might as
> well
> convert to [Char]
> And indexing by Int is O(n) for String and O(1) for ByteString.
> So there are few algorithm that can access both efficiently.
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