Jon Fairbairn says:
On 9 Sep, John Launchbury wrote:
> When we discussed this before I appealed for someone to try it out and
> report on the results:
> * What slowdowns (?speedups) can be expected in practice using Integer
> rather than Int?
> * Do existing programs break wildly with this more general type, or
> do they work just as before? Or do they still work but now produce
> different answers than before.
>
> Please can someone who feels strongly that we should make these changes
> perform some experiments and report the results.
Re speed: please don't! I don't see how knowing about the speed of
existing implementations can affect the reasoning in deciding to make
the change.
I'm with John L on this one.
Standard Haskell is supposed to be a conservative bugfix of 1.4, which can
remain stable. A change that might bring a slowdown of 4-5x is not
conservative; appealing to the ingenuity of future compiler writers won't
bring stability. Unless this change can be proved cheap BEFORE Standard
Haskell is fixed, it should be left out. Otherwise the speed of existing
implementations is exactly what we should reason about, since it is these
which we expect will be the durable implementations of Standard Haskell.
John Hughes
