CODEWITHSUNDEEP
sqlprologtranspiler
BCS
BCS

Reputation: 78683

prolog to SQL converter

Without thinking to much, it seems to me that a large set of Prolog's functionality could be implemented as relational calculus (a.k.a. SQL).

Has anyone heard of any tools to automatically convert Prolog to SQL?

Upvotes: 18

Views: 5974

Answers (6)

Erik Kaplun
Erik Kaplun

Reputation: 38257

CQL, a SWI Prolog add-on pack, compiles Prolog, or rather a Prolog DSL, to SQL:

https://www.swi-prolog.org/pldoc/man?section=cql-examples

Upvotes: 0

Anderson Green
Anderson Green

Reputation: 31850

I wrote a translator that converts a subset of Prolog into SQL user-defined functions.

This predicate in Prolog can be translated into SQL:

is_between(A,B,C) :- 
    A<B,B<C.

This is the translator's output as a MySQL function:

CREATE FUNCTION is_between(A double,B double,C double) RETURNS BIT BEGIN 
    RETURN A>B and B>C;
END

Similarly, there is a Prolog-to-SQL compiler compiler for SWI-Prolog, and another translator that converts a non-recursive subset of Datalog into SQL.

Upvotes: 1

Chrissy Flang&#233; Allen
Chrissy Flang&#233; Allen

Reputation: 68

Recommending:

https://www.cs.cmu.edu/afs/cs/project/ai-repository/ai/lang/prolog/code/io/pl2sql/0.html

my advice- use Eclipse prolog (http://www.eclipseclp.org/) (not (here) to be confused with prolog in the eclipse IDE).

I spent hours trying to get the code to compile in 4 other prologs(!) and 4 minutes to compile in eclipse.

When it works, it's a thing of beauty.

Credit to Herr Draxler of course

Upvotes: 4

Timothy Allen
Timothy Allen

Reputation: 29

It makes more sense to do an sql query from prolog, which can then be translated into prolog facts. e.g. Prolog ODBC Library

This removes all restrictions and keeps the two languages separated into their proper places.

Upvotes: 2

MaD70
MaD70

Reputation: 4158

Yes, of course.

A premise for skeptics: any semi-decent book on database theory mentions Datalog (which is Prolog-like) and theorems which demonstrate that is possible to translate it to/from Relational Algebra (RA) (under specific restrictions).

SQL is not faithful to RA or relational calculi, but is enough to support Prolog:

Upvotes: 35

MarkusQ
MarkusQ

Reputation: 21950

The mapping isn't very good. SQL, for example, doesn't do backtracking, unification, lists, or adhoc nested structures.

Prolog doesn't deal well with composite objects, indexes, etc.

I'd say it's a no-go.

Upvotes: 3

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