." Man page for trealla(1)
.TH trealla 1 "January 2026" "Trealla Prolog" "User Commands"

.SH NAME
trealla, tpl \- A compact, efficient Prolog interpreter

.SH SYNOPSIS
.B tpl
[\fIoptions\fR] [\fIfiles\fR] [\fB--\fR \fIargs\fR]

.SH DESCRIPTION
.B Trealla Prolog
is a compact, efficient Prolog interpreter with ISO Prolog aspirations. It can be used to run Prolog scripts or as an interactive Read-Eval-Print Loop (REPL).

It supports unbounded integers and rationals, UTF-8 atoms, and provides a rich standard library, including an FFI (Foreign Function Interface), concurrency, and database access.

.SH OPTIONS
.TP
\fB-O0, --noopt\fR
Disable optimization.
.TP
\fB-f\fR \fIfile\fR
Load specified \fIfile\fR. The \fI~/.tplrc\fR file is not loaded.
.TP
\fB-l\fR \fIfile\fR
Load specified \fIfile\fR. The \fI~/.tplrc\fR file is loaded.
.TP
\fB-g\fR \fIgoal\fR
Query specified \fIgoal\fR. This option is only used once.
.TP
\fB--library\fR \fIpath\fR
Set an alternative library path, overriding the TPL_LIBRARY_PATH environment variable.
.TP
\fB-t, --trace\fR
Enable trace mode.
.TP
\fB-q, --quiet\fR
Quiet mode, suppresses the startup banner.
.TP
\fB-v, --version\fR
Display Trealla version.
.TP
\fB-h, --help\fR
Display the help message.
.TP
\fB-d, --daemonize\fR
Run the process as a daemon.
.TP
\fB-w, --watchdog\fR
Create a watchdog process.
.TP
\fB--autofail\fR
Cause toplevel queries to fail automatically after the first solution.
.TP
\fB--consult\fR
Consult (load) Prolog source from standard input (STDIN).

.SH FILES
.TP
\fI~/.tplrc\fR
User startup file. It is consulted when the REPL starts unless the \fB-f\fR option is used.

.SH ENVIRONMENT
.TP
\fBTPL_LIBRARY_PATH\fR
Can be used to set the path where Trealla looks for its library files.

.SH EXIT STATUS
.B tpl
exits with a status of 0 on success and with a non-zero value if an error occurs. The \fBhalt/1\fR predicate can be used to exit with a specific status code.

.SH EXAMPLES
.PP
Start the interactive REPL:
.RS
.EX
$ tpl
?- write('Hello, World!'), nl.
Hello, World!
true.
?- halt.
.EE
.RE
.PP
Run a script file:
.RS
.EX
$ tpl my_script.pl
.EE
.RE
.PP
Execute a query from the command line and exit:
.RS
.EX
$ tpl -g "member(3, [1,2,3]), halt."
.EE
.RE

.SH AUTHOR
Written by Andrew Davison and contributors.
Project page: https://github.com/trealla-prolog/trealla

.SH SEE ALSO
swi-prolog(1), gprolog(1)