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Groups > comp.lang.prolog > #14629
| From | Mild Shock <janburse@fastmail.fm> |
|---|---|
| Newsgroups | comp.lang.prolog |
| Subject | Scryer Prolog totally clueless how DCGs work |
| Date | 2025-07-09 11:33 +0200 |
| Message-ID | <104ld1i$1vsct$1@solani.org> (permalink) |
Woa! This nonsense really made my day:
https://github.com/mthom/scryer-prolog/discussions/3004
It starts with, where somebody "tried" a declarative DCG
using constraint logic programming:
number_tail(0, 0) --> [].
number_tail(Number, DigitsCount) -->
("," | ""),
digit(Digit),
number_tail(Digits, RestDigitsCount),
{
DigitsCount #= RestDigitsCount + 1,
Number #= Digit * 10 ^ RestDigitsCount + Digits
}.
He then noticed that its not deterministic. And since
it is not deterministic, clause ordering changes the
result when onced via once/1.
LoL
If DCGs had a cut, one would any way do:
number_tail(Number, DigitsCount) -->
("," | ""),
digit(Digit), !,
number_tail(Digits, RestDigitsCount),
{
DigitsCount #= RestDigitsCount + 1,
Number #= Digit * 10 ^ RestDigitsCount + Digits
}.
number_tail(0, 0) --> [].
Push the determinancy into the DCG. Otherwise you have
an explosion of choice points, and a lot of things go
totally wrong.
But the new DCG standard has no cut (!)/2.
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Scryer Prolog totally clueless how DCGs work Mild Shock <janburse@fastmail.fm> - 2025-07-09 11:33 +0200
Lets see what the "experts" say (Was: Scryer Prolog totally clueless how DCGs work) Mild Shock <janburse@fastmail.fm> - 2025-07-09 11:36 +0200
Payed Ass-Lickers all around (Was: Lets see what the "experts" say) Mild Shock <janburse@fastmail.fm> - 2025-07-09 11:38 +0200
Its all about the money, not about quality (Was: Payed Ass-Lickers all around) Mild Shock <janburse@fastmail.fm> - 2025-07-09 11:42 +0200
A case of dumbification by committee membership? (Was: Its all about the money, not about quality) Mild Shock <janburse@fastmail.fm> - 2025-07-09 20:01 +0200
The stack overflow user by the name false (Was: Lets see what the "experts" say) Mild Shock <janburse@fastmail.fm> - 2025-07-15 11:50 +0200
The choice is a little arbitrary from one angle (Re: The stack overflow user by the name false) Mild Shock <janburse@fastmail.fm> - 2025-07-15 11:59 +0200
Prolog PIP-0110: Its a Floating-Point Multiverse? [Stoic Grisu versus Rest of World] (Was: Lets see what the "experts" say) Mild Shock <janburse@fastmail.fm> - 2026-04-29 00:38 +0200
Does Scryer Prolog have all tricks up its sleeves? [Occurs Check] (Was: Scryer Prolog totally clueless how DCGs work) Mild Shock <janburse@fastmail.fm> - 2025-08-04 19:47 +0200
How hard is PIP-0110 to implement? (Was: Does Scryer Prolog have all tricks up its sleeves?) Mild Shock <janburse@fastmail.fm> - 2026-04-26 22:43 +0200
What about the rubber band ~t (Was: How hard is PIP-0110 to implement?) Mild Shock <janburse@fastmail.fm> - 2026-04-27 10:50 +0200
Addendum Bresenham yatter, yatter (Was: What about the rubber band ~t) Mild Shock <janburse@fastmail.fm> - 2026-04-27 16:03 +0200
Testing NVIDIA A10G / XVM Engine v10.2.4 (Permion Federal AI) (Was: Addendum Bresenham yatter, yatter) Mild Shock <janburse@fastmail.fm> - 2026-04-29 02:12 +0200
This could be a serious security vulnerability (Was: Testing NVIDIA A10G / XVM Engine v10.2.4) Mild Shock <janburse@fastmail.fm> - 2026-04-29 02:22 +0200
Logtalk big time salami slicing [For "Whales" (ultra-high rollers)?] (Re: This could be a serious security vulnerability) Mild Shock <janburse@fastmail.fm> - 2026-04-29 11:21 +0200
format/3 that does not have some Spaghetti logic (Was: How hard is PIP-0110 to implement?) Mild Shock <janburse@fastmail.fm> - 2026-04-30 17:49 +0200
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