I disagree. First of all, UHC states explicitly that some features are not supported (and probably never would be). Secondly, it seems like
almost nobody uses (n+k)-patterns, and when they are used, they make the code less readable; so it's good NOT to support them, in order to make
programmers avoid them as much as possible. I don't think #ifdef's would be really "all over the place"; it's more likely that a minor
refactoring would take place so that (n+k)-patterns would disappear.
Jon Fairbairn wrote on 20.04.2009 13:59:
Achim Schneider <bars...@web.de> writes:
Jon Fairbairn <jon.fairba...@cl.cam.ac.uk> wrote:
a...@cs.uu.nl writes:
Utrecht Haskell Compiler -- first release, version 1.0.0
========================================================
The UHC team is happy to announce the first public release of the
Utrecht Haskell Compiler (UHC). UHC supports almost all Haskell98
features
Why? Is there something about Haskell 98 that's hard to
implement?
Insanity. I doubt anyone is going to miss n+k patterns:
That (taken with the followup from Richard O'Keefe saying he
does use them) underlines my point, really. What follows is
specific to Haskell, but the general point applies to most
languages I've encountered.
I have no love for n+k patterns, but they are part of
Haskell98 -- and were the subject of protracted arguments
for and against them before the Report was finished (I was
against them, if I remember correctly). Any implementation
claiming to be of Haskell98 should have them, whether or not
the implementor likes them, because otherwise someone will
come along with a valid Haskell98 programme and it won't
compile, so they'll have to hack it around. This sort of
thing (and resulting #ifdef all over the place) wastes far
more programmer time in the end (assuming the compiler
becomes popular) than it would take to implement the
feature.
It's not an implementor's place to make such decisions --
they can legitimately say "this feature sucks" and tell the
next Haskell committee so. If they care enough about it,
they can lobby or get on that next committee, but the
arguments for n+k patterns /in Haskell98/ were done long
ago.
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