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

Flowlog Quick Start (`flowlog.c`)

This quick start covers Flowlog built from flowlog.c.

Build

Build with the Makefile in the parent directory:

make

Or build directly with a C compiler:

cc -O2 -Wall -Wextra -pthread flowlog.c -lm -o flowlog

Run

REPL (interactive)

Start the REPL with an empty [user] program:

./flowlog

Start the REPL with a program loaded:

./flowlog program.pl

Load multiple files (RC file first):

./flowlog program1.pl program2.pl

Fast startup (skip RC file):

./flowlog -f
./flowlog --fast

Run a one-shot query

./flowlog -g "goal." program.pl

Notes:

Queries should end with . (ISO style).
Startup RC file defaults to ~/.flowlogrc (override via FLOWLOG_RC_FILE).
System CLI flags are parsed only before the first positional file.
After the first positional file, existing regular-file tokens begin new file segments.
Tokens between file segments are per-file application argv, visible via current_prolog_flag(argv, A) as a list of strings.
current_prolog_flag(argv, A) resolves by calling source file during predicate execution; at top level it shows the default segment (first positional file, or []).
On a TTY, Flowlog prints the first 5 answers automatically, then supports SPACE/;/n (next 5), a (stream all), w/x (print full saved answers), and Enter/. (stop with ...). In non-TTY mode it prints all solutions (SECTION 26).

REPL commands (SECTION 26)

At the ?- prompt:

help. - show help text
halt. / quit. - exit
:load path/to/file.pl - load a program file (replaces the current program)
:reload - reload the last loaded program (file or [file].)
expand. - print full saved answers from the previous query
solutions(X). - replay saved answers one-by-one
[file]. - load a program file (consult-style top-level convenience)

Notes:

The REPL evaluates normal Prolog goals (ending in .).
[file]. is a top-level convenience commonly supported by other Prolog systems; in Flowlog it loads one or more source files and replaces the currently loaded program (similar to :load).

Line editing and history (TTY) (SUBSECTION 26.2)

When stdin/stdout are a real terminal (TTY), the REPL enables:

History (default: ~/.flowlog_history, override with FLOWLOG_HISTORY_FILE)
Common line editing keys, including:
- Ctrl-P / Ctrl-N (previous/next history)
- Arrow keys, Home/End
- Ctrl-A / Ctrl-E, Ctrl-B / Ctrl-F (cursor movement)
- Ctrl-U / Ctrl-K, Backspace/Delete
Ctrl-X is a REPL shortcut for printing full saved answers from the previous query, while keeping the current input line.

When not a TTY (pipes, redirected input), prompts and banners are suppressed and Flowlog reads from stdin line-by-line.

Defining predicates at runtime (SECTION 13)

The portable way to define or extend predicates interactively is to use the ISO dynamic database:

?- assertz((parent(alice, bob))),
   assertz((parent(bob, claire))),
   assertz((ancestor(A, B) :- parent(A, B))).

In practice, most programs are written in .pl files and loaded with :load (REPL) or by passing the file name on the command line.

Parallelism (default)

Flowlog runs queries with the fast parallel profile by default (unordered OR-par for throughput) (SECTION 25 and SECTION 21).

?- Goal.

Thread count:

Defaults to the system’s online CPU count (SUBSECTION 04.2).
Override with --threads N or FLOWLOG_N_CPUPROC=N (SUBSECTION 26.1 and SUBSECTION 04.2).

If you need classic ordered behavior, run with:

--parallel-profile iso (parallel, ordered commits) (SUBSECTION 26.1), or
--parallel-profile off (sequential) (SUBSECTION 26.1)

See PARALLELISM.md for semantics and tuning.

Engine selection (optional)

Flowlog defaults to --engine wamvm (SECTION 25).

To force the WAM-lite engine (useful for tabling workloads) (SECTION 23 and SECTION 20):

./flowlog --engine wam -g "goal." program.pl

To force the reference interpreter (SECTION 22):

./flowlog --engine tree -g "goal." program.pl

Tests

If you have the full Flowlog repository checkout, see CONFORMANCE.md for the recommended ISO/regression test suites and where to run them from.

Flowlog Quick Start (flowlog.c)