JANET(1) User Commands JANET(1)

NAME

janet - run the Janet language abstract machine

SYNOPSIS

janet [-hvsrpnqik] [-e SOURCE] [-E SOURCE ...ARGUMENTS] [-l MODULE]
[-m PATH] [-c MODULE JIMAGE] [-w LEVEL] [-x LEVEL] [--] script
args...

DESCRIPTION

Janet is a functional and imperative programming language and
bytecode interpreter. It is a Lisp-like language, but lists are
replaced by other data structures (arrays, tables, structs, tuples).
The language also features bridging to native code written in C,
meta-programming with macros, and bytecode assembly.

There is a repl for trying out the language, as well as the ability
to run script files. This client program is separate from the core
runtime, so Janet could be embedded into other programs. Try Janet in
your browser at https://janet-lang.org.

Implemented in mostly standard C99, Janet runs on Windows, Linux and
macOS. The few features that are not standard C99 (dynamic library
loading, compiler specific optimizations), are fairly straight
forward. Janet can be easily ported to most new platforms.


REPL KEY-BINDINGS
Home Move cursor to the beginning of input line.


End Move cursor to the end of input line.


Left/Right Move cursor in input line.


Up/Down Go backwards and forwards through history.


Tab Complete current symbol, or show available
completions.


Delete Delete one character after the cursor.


Backspace Delete one character before the cursor.


Ctrl-A Move cursor to the beginning of input line.


Ctrl-B Move cursor one character to the left.


Ctrl-D If on a newline, indicate end of stream and exit the
repl.


Ctrl-E Move cursor to the end of input line.


Ctrl-F Move cursor one character to the right.


Ctrl-H Delete one character before the cursor.


Ctrl-K Delete everything after the cursor on the input line.


Ctrl-L Clear the screen.


Ctrl-N/Ctrl-P Go forwards and backwards through history.


Ctrl-U Delete everything before the cursor on the input
line.


Ctrl-W Delete one word before the cursor.


Ctrl-G Show documentation for the current symbol under the
cursor.


Ctrl-Q Clear the current command, including already typed
lines.


Alt-B/Alt-F Move cursor backwards and forwards one word.


Alt-D Delete one word after the cursor.


Alt-, Go to earliest item in history.


Alt-. Go to last item in history.


The repl keybindings are loosely based on a subset of GNU readline,
although Janet does not use GNU readline internally for the repl. It
is a limited substitute for GNU readline, and does not handle utf-8
input or other mutlibyte input well.

To disable the built-in repl input handling, pass the -s option to
Janet, and use a program like rlwrap with Janet to provide input.

For key bindings that operate on words, a word is considered to be a
sequence of characters that does not contain whitespace.

DOCUMENTATION

For more complete API documentation, run a REPL (Read Eval Print
Loop), and use the doc macro to see documentation on individual
bindings.

OPTIONS

-h Shows the usage text and exits immediately.


-v Shows the version text and exits immediately.


-s Read raw input from stdin and forgo prompt history and other
readline-like features.


-e code
Execute a string of Janet source. Source code is executed in
the order it is encountered, so earlier arguments are executed
before later ones.


-E code arguments...
Execute a single Janet expression as a Janet short-fn, passing
the remaining command line arguments to the expression. This
allows more concise one-liners with command line arguments.

Example: janet -E '(print $0)' 12 is equivalent to '((short-fn
(print $0)) 12)', which is in turn equivalent to `((fn [k]
(print k)) 12)`

See docs for the `short-fn` function for more details.


-d Enable debug mode. On all terminating signals as well the
debug signal, this will cause the debugger to come up in the
REPL. Same as calling (setdyn :debug true) in a default repl.


-n Disable ANSI colors in the repl. Has no effect if no repl is
run.


-N Enable ANSI colors in the repl. Has no effect if no repl is
run.


-r Open a REPL (Read Eval Print Loop) after executing all
sources. By default, if Janet is called with no arguments, a
REPL is opened.


-R If using the REPL, disable loading the user profile from the
JANET_PROFILE environment variable.


-p Turn on the persistent flag. By default, when Janet is
executing commands from a file and encounters an error, it
will immediately exit after printing the error message. In
persistent mode, Janet will keep executing commands after an
error. Persistent mode can be good for debugging and testing.


-q Hide the logo in the repl.


-k Don't execute a script, only compile it to check for errors.
Useful for linting scripts.


-m syspath
Set the dynamic binding :syspath to the string syspath so that
Janet will load system modules from a directory different than
the default. The default is set when Janet is built, and
defaults to /usr/local/lib/janet on Linux/Posix, and
C:/Janet/Library on Windows. This option supersedes
JANET_PATH.


-c source output
Precompiles Janet source code into an image, a binary dump
that can be efficiently loaded later. Source should be a path
to the Janet module to compile, and output should be the file
path of resulting image. Output should usually end with the
.jimage extension.


-i When this flag is passed, a script passed to the interpreter
will be treated as a janet image file rather than a janet
source file.


-l lib Import a Janet module before running a script or repl.
Multiple files can be loaded in this manner, and exports from
each file will be made available to the script or repl.

-w level
Set the warning linting level for Janet. This linting level
should be one of :relaxed, :none, :strict, :normal, or a Janet
number. Any linting message that is of a greater lint level
than this setting will be displayed as a warning, but not stop
compilation or execution.

-x level
Set the error linting level for Janet. This linting level
should be one of :relaxed, :none, :strict, :normal, or a Janet
number. Any linting message that is of a greater lint level
will cause a compilation error and stop compilation.

-- Stop parsing command line arguments. All arguments after this
one will be considered file names and then arguments to the
script.

ENVIRONMENT

JANET_PATH
The location to look for Janet libraries. This is the only
environment variable Janet needs to find native and source
code modules. If no JANET_PATH is set, Janet will look in the
default location set at compile time.

JANET_PROFILE
Path to a profile file that the interpreter will load before
entering the REPL. This profile file will not run for scripts,
though. This behavior can be disabled with the -R option.

JANET_HASHSEED
To disable randomization of Janet's PRF on start up, one can
set this variable. This can have the effect of making programs
deterministic that otherwise would depend on the random seed
chosen at program start. This variable does nothing in the
default configuration of Janet, as PRF is disabled by default.
Also, JANET_REDUCED_OS cannot be defined for this variable to
have an effect.

NO_COLOR
Turn off color by default in the repl and in the error handler
of scripts. This can be changed at runtime via dynamic
bindings *err-color* and *pretty-format*, or via the command
line parameters -n and -N.

AUTHOR

Written by Calvin Rose <calsrose@gmail.com>

JANET(1)