CHR
1 program
Added 2026-02-23T10:00:00Z
Agent: claude-codeModel: claude-sonnet-4-6WebSearch: enabled
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Aliases: Constraint Handling Rules
Provenance: commit 0b98c1f817 · authored 2026-02-23T18:15:29+01:00 · agent claude-code · model claude-sonnet-4-6
Sources mentioning this language
5 sources · pl_id:
pl/chrWikipedia infobox ↗
Pulled from the
wikimedia/structured-wikipedia
snapshot — see data/raw/wikipedia_pl_facts.*.jsonl and
pl_fact.csv for the long-table provenance.
| Paradigms | constraint logic · declarative |
|---|---|
| Designed by | Thom Frühwirth |
| First appeared | 1991 |
| Influenced by | Prolog |
Related languages
Real programs from Software Heritage
No SWH evidence indexed yet for this language. (Either the SWH mining hasn't reached this language's extensions, or no matching files exist in the archive.)
Programs collected by LLM agents experimental · unverified
Gathered by LLM agents during the experiment that started this catalogue. They are not verified: the agent names an origin, but a program can be altered or invented — an audit found one attributed to a file that does not exist, in a syntax the language does not have. Prefer the programs archived by Software Heritage above. The catalogue's goal is the languages themselves, grounded in sources (PLDB, Wikipedia, Rosetta Code, …), with real archived programs; these examples may be dropped.
Fibonacci via CHR Tabulation
Provenance: commit 0b98c1f817 · authored 2026-02-23T18:15:29+01:00 · agent claude-code · model claude-sonnet-4-6 · WebSearch enabled
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%%
%% 16 June 2003 Bart Demoen, Tom Schrijvers, K.U.Leuven
%%
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:- module(fibonacci,[]).
:- use_module(library(chr)).
:- constraints fibonacci/2.
%% fibonacci(N,M) is true iff M is the Nth Fibonacci number.
%% Top-down Evaluation with effective Tabulation
%% Contrary to the version in the SICStus manual, this one does "true"
%% tabulation
fibonacci(N,M1) # Id \ fibonacci(N,M2) <=> var(M2) | M1 = M2 pragma passive(Id).
fibonacci(0,M) ==> M = 1.
fibonacci(1,M) ==> M = 1.
fibonacci(N,M) ==>
N > 1 |
N1 is N-1,
fibonacci(N1,M1),
N2 is N-2,
fibonacci(N2,M2),
M is M1 + M2.