Re: New PAKCS release (Version 1.8.0)

From: Wolfgang Lux <wlux_at_uni-muenster.de>
Date: Fri, 30 Mar 2007 08:28:20 +0200

Emilio Jesús Gallego Arias wrote:

> As your example showed, current non-determinism in FLP doesn't
> preserve program semantics in simple cases like:
>
> coin = 0
> coin = 1
>
> let x = coin in (x,x)
> !=
> (coin,coin)
>
> [Note that Sloth indeed can spot such simple cases and fix them, but
> it doesn't work in general, with eta-expansion and so on.]

Sorry, I don't understand that remark. Curry uses call-time choice
which means that both expressions are not equal. I do not see what
Sloth can do about this. The only option to make both expressions
equal I see is using a run-time choice semantics. There may be good
arguments for run-time choice, but it looks difficult to me to
reconcile sharing with run-time choice.

> We dislike semantics where this is not preserved, so perpetuating this
> kind of behavior is not a path we'd like to follow,

Are you asking for a change of Curry's semantics to use run-time choice
instead of call-time choice?

Wolfgang



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Received on Fri Mar 30 2007 - 13:23:50 CEST

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