Markus Triska

Where is the time spent? (Exhibit 5: Salsa20 core)

1

Following the benchmarks given in #207, #315 and #317, here is a Prolog implementation of the [Salsa20 core](https://cr.yp.to/salsa20.html), a powerful stream cipher developed by Dan Bernstein: **https://www.metalevel.at/prolog/scryer/salsa20.pl** The program works by interpreting...

Unexpected loop

2

With `t.pl` comprising: :- use_module(library(iso_ext)). :- use_module(library(format)). :- meta_predicate(t(0)). :- dynamic(id/1). :- dynamic(state/2). next_id(N) :- ( retract(id(N0)) -> N is N0 + 1 ; N = 0 ), asserta(id(N)). t(Goal)...

'$call'/N does not call directly

7

From https://github.com/mthom/scryer-prolog/discussions/1513#discussioncomment-2978271, I take it that `'$call'/N` calls the goal directly, without any expansion. Currently, if I define: p(X) :- '$call'(g, X). then this gets compiled to the WAM instructions:...

Avoiding the overhead of meta-calls in maplist/N and foldl/N by partial evaluation

12

When the first argument of the frequently used meta-predicates `maplist/N` and `foldl/N` is *known* at compilation time (which is the most common case), then the overhead of the meta-call can...

Currently, I get: $ scryer-prolog -f ?- phrase("", ""). true. That is: `phrase/2` is defined even though `library(dcgs)` is not loaded. This seems a bit more "unexpected" than #987, and...

error(syntax_error(inadmissible_query_term),load/1)

1

Currently, I get: $ scryer-prolog ?- [user]. p :- "test". error(syntax_error(inadmissible_query_term),load/1). Expected: Successful compilation, on the grounds that the program is syntactically correct.

¤ cannot be used

12

Currently, I get: ?- X = ¤. error(syntax_error(unexpected_char),read_term/3:0). ?- X = '¤'. error(syntax_error(invalid_single_quoted_character),read_term/3). ?- X = "¤". error(syntax_error(missing_quote),read_term/3:0). Is there anything special about this character? Why cannot it be used...

Argument indexing sometimes does not exclude clauses that cannot apply

6

For example, with `p/1` defined as: p(E) :- var(E). p(E) :- integer(E). p(a). I get: ?- p(0). true ; false. Expected: **Deterministic success**, because `p(a)` does not apply on the...

ADDED: library(options)

6

This library is mostly intended for authors of other *libraries*. I did not even mention it in the `README`, because it only contains a single predicate: `option/3`, to ask whether...

DOC: Describe how to use "p" and "w" on the toplevel to write terms without depth limit.

5

This is motivated by https://github.com/mthom/scryer-prolog/issues/384#issuecomment-902709060 .