^ ^                 ^ ^
=(o.o)=  ~byakuren  =(o.o)=
  m m                 m m

release plan

• 4.8.x - fix command line arguments
• • [flowlog args] filename [program args]
• 4.9.x - fix conformancy one by one
• 5.0.x - bit streams (with byte…etc structures)
• 5.1.x - attributed variables

things to do c:

• make quad should be engine dependant to get full coverage and results
  • make quad will run 3 loops, one for each engine by default
  • rename generated files in results/ to include the engine used for the test
• wasm make target
• add DCG support
• add shell/n predicates
  • allow running system commands and getting output/sending input
  • works great with DCG’s for parsing output
• add more readline bindings for line editing
• fix strings to show as "strings" rather than [s, t, r, i, n, g, s]
• test conformity better
  • quick test: how many strings of length N parse to valid integeres
    • https://github.com/trealla-prolog/trealla/issues/825#issue-3190642900
    • needs countall/2
    • number_chars/2 is good test because it tests the parser
    • watch out for embedded, and escape sequences
  • comprehensive test:
    • https://www.complang.tuwien.ac.at/ulrich/iso-prolog/conformity_testing
    • let’s get to 100% some day c:
    • test input is sent to read(G_0), G_0. or …
    • this way it tests reading and writing
    • can quickly do it in emacs: https://www.youtube.com/watch?v=Ko_IrwN9yAM
• reliable timeout and space-out errors
  • (scryer) call_with_inference_limit
  • (SICStus) call_with_time_limit/3 time_out/3 https://sicstus.sics.se/sicstus/docs/3.12.7/html/sicstus/Timeout.html
• implement attributed variables
  • would allow for parallel constraint solving
  • start with dif/2 (scryer:dif.pl)
  • then CLP(B)
  • then clpz
• writing terms should be moved to prolog code
  • writing cannot tell any difference in internal representation
  • can potentially move most of the parser to prolog, keeping just axiomatic code in c

uwn https://www.complang.tuwien.ac.at/ulrich/flowlog-prolog/

5. testing number_chars/2 Because of #3 and #4, I cannot use the current test table, so I resorted to the old one. Please go through it. Problems start with #9, #17, #21.

    ulrich@gupu:/opt/gupu/flowlog$ ./flowlog 
    Flowlog (pthreads)
    Type 'help.' for help, 'halt.' to exit.
    ?- number_chars(1,[_,[]]).
    error(instantiation_error,/(number_chars,2)), unexpected.
       type_error(character,[]). % expected, but not found
    ?- number_chars(N,['3',.]).
    N = 3.0, unexpected.
       syntax_error(...). % expected, but not found
    ?- number_chars(N,[-,' ','1']).
    flowlog: fatal error (240): flowlog: unexpected token while parsing term

6. writeq ignores operators Before improving read-ing, consider writeq-ing. Such that you always write valid syntax. So the first to address would be:

   1. s#1
   2. s#13
   3. s#27
   4. s#35
   5. s#36

7. select/3 not conforming Since 2011 select/3 is defined without any errors. Just with two clauses. (Actually, it was commonly defined like that since at least 1983. C&M:1981 did not use it) Thus the following is not conforming:

    ?- select(X, Xs, Ys).
    false, unexpected.
    ?- select(X, Xs, Xs).
    false, unexpected. % see p.p.5.4
    ?- select(X,Xs,[1,2,3]).
    false, unexpected.
    % this is the expected answer:
       Xs = [X,1,2,3]
    ;  Xs = [1,X,2,3]
    ;  Xs = [1,2,X,3]
    ;  Xs = [1,2,3,X].
    ?- select(X, [Y|nonlist], Xs).
    error(type_error(list,[_G0|nonlist]),/(select1,3)), unexpected.

This type error would make sense, if the template and modes subclause would indicate ?list for the second argument, but it reads in p.p.5.2

        select(?term, ?term, ?term)

    ?- Xs = [a|Xs], ( true ; catch(select(X, Xs, Ys), Err, true ) ).
       Xs = [a,a,a,a,a|...]
    ;  Xs = [a,a,a,a,a|...], error(representation_error(term),/(select1,3)), unexpected.
    % expected behaviour:
       sto,
       false % occurs-check
    |  sto,
       Xs = [a|Xs] % rational trees
    ;  Xs = [a|Xs], X = a, Ys = [a|Ys]
    ;  Xs = [a|Xs], X = a, Ys = [a|Ys]
    ;  ..., ad_infinitum
    |  sto,
       representation_error(term).

11. append/3 does not work (Example from the Prolog prologue)

    ?- append([a], Ys, Zs).
    Segmentation fault (core dumped), unexpected.
       Zs = [a|Ys]. % expected, but not found

v4.6.5