mirror of
https://github.com/janet-lang/janet
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236 lines
8.9 KiB
Markdown
236 lines
8.9 KiB
Markdown
[](https://gitter.im/janet-language/community)
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[](https://ci.appveyor.com/project/bakpakin/janet/branch/master)
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[](https://travis-ci.org/janet-lang/janet)
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[](https://builds.sr.ht/~bakpakin/janet/freebsd.yml?)
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[](https://builds.sr.ht/~bakpakin/janet/openbsd.yml?)
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<img src="https://raw.githubusercontent.com/janet-lang/janet/master/assets/janet-w200.png" alt="Janet logo" width=200 align="left">
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**Janet** is a functional and imperative programming language and bytecode interpreter. It is a
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modern lisp, but lists are replaced
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by other data structures (arrays, tables (hash table), struct (immutable hash table), tuples).
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The language also supports bridging to native code written in C, meta-programming with macros, and bytecode assembly.
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There is a repl for trying out the language, as well as the ability
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to run script files. This client program is separate from the core runtime, so
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Janet can be embedded into other programs. Try Janet in your browser at
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[https://janet-lang.org](https://janet-lang.org).
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<br>
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## Use Cases
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Janet makes a good system scripting language, or a language to embed in other programs.
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It's like Lua and Guile in that regard. It has more built-in functionality and a richer core language than
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Lua, but smaller than GNU Guile or Python.
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## Features
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* Minimal setup - one binary and you are good to go!
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* First class closures
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* Garbage collection
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* First class green threads (continuations)
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* Python style generators (implemented as a plain macro)
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* Mutable and immutable arrays (array/tuple)
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* Mutable and immutable hashtables (table/struct)
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* Mutable and immutable strings (buffer/string)
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* Lisp Macros
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* Byte code interpreter with an assembly interface, as well as bytecode verification
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* Tailcall Optimization
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* Direct interop with C via abstract types and C functions
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* Dynamically load C libraries
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* Functional and imperative standard library
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* Lexical scoping
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* Imperative programming as well as functional
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* REPL
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* Parsing Expression Grammars built in to the core library
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* 400+ functions and macros in the core library
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* Embedding Janet in other programs
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* Interactive environment with detailed stack traces
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## Documentation
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* For a quick tutorial, see [the introduction](https://janet-lang.org/docs/index.html) for more details.
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* For the full API for all functions in the core library, see [the core API doc](https://janet-lang.org/api/index.html)
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Documentation is also available locally in the repl.
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Use the `(doc symbol-name)` macro to get API
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documentation for symbols in the core library. For example,
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```
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(doc doc)
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```
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Shows documentation for the doc macro.
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To get a list of all bindings in the default
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environment, use the `(all-bindings)` function. You
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can also use the `(doc)` macro with no arguments if you are in the repl
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to show bound symbols.
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## Source
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You can get the source on [GitHub](https://github.com/janet-lang/janet) or
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[SourceHut](https://git.sr.ht/~bakpakin/janet). While the GitHub repo is the official repo,
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the SourceHut mirror is actively maintained.
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## Building
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### macos and Unix-like
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The Makefile is non-portable and requires GNU-flavored make.
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```
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cd somewhere/my/projects/janet
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make
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make test
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make repl
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```
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### 32-bit Haiku
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32-bit Haiku build instructions are the same as the unix-like build instructions,
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but you need to specify an alternative compiler, such as `gcc-x86`.
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```
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cd somewhere/my/projects/janet
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make CC=gcc-x86
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make test
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make repl
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```
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### FreeBSD
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FreeBSD build instructions are the same as the unix-like build instuctions,
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but you need `gmake` to compile. Alternatively, install directly from
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packages, using `pkg install lang/janet`.
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```
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cd somewhere/my/projects/janet
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gmake
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gmake test
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gmake repl
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```
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### Windows
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1. Install [Visual Studio](https://visualstudio.microsoft.com/thank-you-downloading-visual-studio/?sku=Community&rel=15#) or [Visual Studio Build Tools](https://visualstudio.microsoft.com/thank-you-downloading-visual-studio/?sku=BuildTools&rel=15#)
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2. Run a Visual Studio Command Prompt (cl.exe and link.exe need to be on the PATH) and cd to the directory with janet.
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3. Run `build_win` to compile janet.
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4. Run `build_win test` to make sure everything is working.
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### Meson
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Janet also has a build file for [Meson](https://mesonbuild.com/), a cross platform build
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system. Although Meson has a python dependency, Meson is a very complete build system that
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is maybe more convenient and flexible for integrating into existing pipelines.
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Meson also provides much better IDE integration than Make or batch files, as well as support
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for cross compilation.
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For the impatient, building with Meson is as follows. The options provided to
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`meson setup` below emulate Janet's Makefile.
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```sh
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git clone https://github.com/janet-lang/janet.git
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cd janet
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meson setup build \
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--buildtype release \
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--optimization 2 \
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-Dgit_hash=$(git log --pretty=format:'%h' -n 1)
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ninja -C build
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# Run the binary
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build/janet
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# Installation
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ninja -C build install
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```
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## Development
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Janet can be hacked on with pretty much any environment you like, but for IDE
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lovers, [Gnome Builder](https://wiki.gnome.org/Apps/Builder) is probably the
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best option, as it has excellent meson integration. It also offers code completion
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for Janet's C API right out of the box, which is very useful for exploring. VSCode, Vim,
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Emacs, and Atom will have syntax packages for the Janet language, though.
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## Installation
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See [the Introduction](https://janet-lang.org/introduction.html) for more details. If you just want
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to try out the language, you don't need to install anything. You can also move the `janet` executable wherever you want on your system and run it.
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## Usage
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A repl is launched when the binary is invoked with no arguments. Pass the -h flag
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to display the usage information. Individual scripts can be run with `./janet myscript.janet`
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If you are looking to explore, you can print a list of all available macros, functions, and constants
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by entering the command `(all-bindings)` into the repl.
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```
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$ janet
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Janet 1.7.1-dev-951e10f Copyright (C) 2017-2020 Calvin Rose
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janet:1:> (+ 1 2 3)
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6
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janet:2:> (print "Hello, World!")
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Hello, World!
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nil
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janet:3:> (os/exit)
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$ janet -h
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usage: build/janet [options] script args...
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Options are:
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-h : Show this help
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-v : Print the version string
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-s : Use raw stdin instead of getline like functionality
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-e code : Execute a string of janet
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-r : Enter the repl after running all scripts
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-p : Keep on executing if there is a top level error (persistent)
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-q : Hide prompt, logo, and repl output (quiet)
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-k : Compile scripts but do not execute (flycheck)
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-m syspath : Set system path for loading global modules
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-c source output : Compile janet source code into an image
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-n : Disable ANSI color output in the repl
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-l path : Execute code in a file before running the main script
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-- : Stop handling options
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```
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If installed, you can also run `man janet` and `man jpm` to get usage information.
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## Embedding
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Janet can be embedded in a host program very easily. The normal build
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will create a file `build/janet.c`, which is a single C file
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that contains all the source to Janet. This file, along with
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`src/include/janet.h` and `src/include/janetconf.h` can dragged into any C
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project and compiled into the project. Janet should be compiled with `-std=c99`
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on most compilers, and will need to be linked to the math library, `-lm`, and
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the dynamic linker, `-ldl`, if one wants to be able to load dynamic modules. If
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there is no need for dynamic modules, add the define
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`-DJANET_NO_DYNAMIC_MODULES` to the compiler options.
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See the [Embedding Section](https://janet-lang.org/capi/embedding.html) on the website for more information.
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## Examples
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See the examples directory for some example janet code.
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## Discussion
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Feel free to ask questions and join discussion on the [Janet Gitter Channel](https://gitter.im/janet-language/community).
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Alternatively, check out [the #janet channel on Freenode](https://webchat.freenode.net/)
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## FAQ
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### Why is my terminal is spitting out junk when I run the repl?
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Make sure your terminal supports ANSI escape codes. Most modern terminals will
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support these, but some older terminals, windows consoles, or embedded terminals
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will not. If your terminal does not support ANSI escape codes, run the repl with
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the `-n` flag, which disables color output. You can also try the `-s` if further issues
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ensue.
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## Why Janet
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Janet is named after the almost omniscient and friendly artificial being in [The Good Place](https://en.wikipedia.org/wiki/The_Good_Place).
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<img src="https://raw.githubusercontent.com/janet-lang/janet/master/assets/janet-the-good-place.gif" alt="Janet logo" width="115px" align="left">
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