1JANET(1) General Commands Manual JANET(1)
2
6 janet - run the Janet language abstract machine
7
9 janet [-hvsrpnqik] [-e SOURCE] [-E SOURCE ...ARGUMENTS] [-l MODULE] [-m
10 PATH] [-c MODULE JIMAGE] [-w LEVEL] [-x LEVEL] [--] script args...
11
13 Janet is a functional and imperative programming language and bytecode
14 interpreter. It is a Lisp-like language, but lists are replaced by
15 other data structures (arrays, tables, structs, tuples). The language
16 also features bridging to native code written in C, meta-programming
17 with macros, and bytecode assembly.
18 There is a repl for trying out the language, as well as the ability to
20 run script files. This client program is separate from the core run‐
21 time, so Janet could be embedded into other programs. Try Janet in your
22 browser at https://janet-lang.org.
23 Implemented in mostly standard C99, Janet runs on Windows, Linux and
25 macOS. The few features that are not standard C99 (dynamic library
26 loading, compiler specific optimizations), are fairly straight forward.
27 Janet can be easily ported to most new platforms.
28
31 Home Move cursor to the beginning of input line.
32 End Move cursor to the end of input line.
35 Left/Right Move cursor in input line.
38 Up/Down Go backwards and forwards through history.
41 Tab Complete current symbol, or show available completions.
44 Delete Delete one character after the cursor.
47 Backspace Delete one character before the cursor.
50 Ctrl-A Move cursor to the beginning of input line.
53 Ctrl-B Move cursor one character to the left.
56 Ctrl-D If on a newline, indicate end of stream and exit the
59 repl.
60 Ctrl-E Move cursor to the end of input line.
63 Ctrl-F Move cursor one character to the right.
66 Ctrl-H Delete one character before the cursor.
69 Ctrl-K Delete everything after the cursor on the input line.
72 Ctrl-L Clear the screen.
75 Ctrl-N/Ctrl-P Go forwards and backwards through history.
78 Ctrl-U Delete everything before the cursor on the input line.
81 Ctrl-W Delete one word before the cursor.
84 Ctrl-G Show documentation for the current symbol under the
87 cursor.
88 Ctrl-Q Clear the current command, including already typed
91 lines.
92 Alt-B/Alt-F Move cursor backwards and forwards one word.
95 Alt-D Delete one word after the cursor.
98 Alt-, Go to earliest item in history.
101 Alt-. Go to last item in history.
104 The repl keybindings are loosely based on a subset of GNU readline, al‐
107 though Janet does not use GNU readline internally for the repl. It is a
108 limited substitute for GNU readline, and does not handle utf-8 input or
109 other mutlibyte input well.
110 To disable the built-in repl input handling, pass the -s option to
112 Janet, and use a program like rlwrap with Janet to provide input.
113 For key bindings that operate on words, a word is considered to be a
115 sequence of characters that does not contain whitespace.
116
119 For more complete API documentation, run a REPL (Read Eval Print Loop),
120 and use the doc macro to see documentation on individual bindings.
121
124 -h Shows the usage text and exits immediately.
125 -v Shows the version text and exits immediately.
128 -s Read raw input from stdin and forgo prompt history and other
131 readline-like features.
132 -e code
135 Execute a string of Janet source. Source code is executed in the
136 order it is encountered, so earlier arguments are executed be‐
137 fore later ones.
138 -E code arguments...
141 Execute a single Janet expression as a Janet short-fn, passing
142 the remaining command line arguments to the expression. This al‐
143 lows more concise one-liners with command line arguments.
144 Example: janet -E '(print $0)' 12 is equivalent to '((short-fn
146 (print $0)) 12)', which is in turn equivalent to `((fn [k]
147 (print k)) 12)`
148 See docs for the `short-fn` function for more details.
150 -d Enable debug mode. On all terminating signals as well the debug
153 signal, this will cause the debugger to come up in the REPL.
154 Same as calling (setdyn :debug true) in a default repl.
155 -n Disable ANSI colors in the repl. Has no effect if no repl is
158 run.
159 -N Enable ANSI colors in the repl. Has no effect if no repl is run.
162 -r Open a REPL (Read Eval Print Loop) after executing all sources.
165 By default, if Janet is called with no arguments, a REPL is
166 opened.
167 -R If using the REPL, disable loading the user profile from the
170 JANET_PROFILE environment variable.
171 -p Turn on the persistent flag. By default, when Janet is executing
174 commands from a file and encounters an error, it will immedi‐
175 ately exit after printing the error message. In persistent mode,
176 Janet will keep executing commands after an error. Persistent
177 mode can be good for debugging and testing.
178 -q Hide the logo in the repl.
181 -k Don't execute a script, only compile it to check for errors.
184 Useful for linting scripts.
185 -m syspath
188 Set the dynamic binding :syspath to the string syspath so that
189 Janet will load system modules from a directory different than
190 the default. The default is set when Janet is built, and de‐
191 faults to /usr/local/lib/janet on Linux/Posix, and C:/Janet/Li‐
192 brary on Windows. This option supersedes JANET_PATH.
193 -c source output
196 Precompiles Janet source code into an image, a binary dump that
197 can be efficiently loaded later. Source should be a path to the
198 Janet module to compile, and output should be the file path of
199 resulting image. Output should usually end with the .jimage ex‐
200 tension.
201 -i When this flag is passed, a script passed to the interpreter
204 will be treated as a janet image file rather than a janet source
205 file.
206 -l lib Import a Janet module before running a script or repl. Multiple
209 files can be loaded in this manner, and exports from each file
210 will be made available to the script or repl.
211 -w level
213 Set the warning linting level for Janet. This linting level
214 should be one of :relaxed, :none, :strict, :normal, or a Janet
215 number. Any linting message that is of a greater lint level than
216 this setting will be displayed as a warning, but not stop compi‐
217 lation or execution.
218 -x level
220 Set the error linting level for Janet. This linting level
221 should be one of :relaxed, :none, :strict, :normal, or a Janet
222 number. Any linting message that is of a greater lint level will
223 cause a compilation error and stop compilation.
224 -- Stop parsing command line arguments. All arguments after this
226 one will be considered file names and then arguments to the
227 script.
228
231 JANET_PATH
232 The location to look for Janet libraries. This is the only envi‐
233 ronment variable Janet needs to find native and source code mod‐
234 ules. If no JANET_PATH is set, Janet will look in the default
235 location set at compile time.
236 JANET_PROFILE
238 Path to a profile file that the interpreter will load before en‐
239 tering the REPL. This profile file will not run for scripts,
240 though. This behavior can be disabled with the -R option.
241 JANET_HASHSEED
243 To disable randomization of Janet's PRF on start up, one can set
244 this variable. This can have the effect of making programs de‐
245 terministic that otherwise would depend on the random seed cho‐
246 sen at program start. This variable does nothing in the default
247 configuration of Janet, as PRF is disabled by default. Also,
248 JANET_REDUCED_OS cannot be defined for this variable to have an
249 effect.
250 NO_COLOR
252 Turn off color by default in the repl and in the error handler
253 of scripts. This can be changed at runtime via dynamic bindings
254 *err-color* and *pretty-format*, or via the command line parame‐
255 ters -n and -N.
256
259 Written by Calvin Rose <calsrose@gmail.com>
260 JANET(1)