mirror of
https://github.com/janet-lang/janet
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179 lines
6.1 KiB
Markdown
179 lines
6.1 KiB
Markdown
# janet
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[](https://travis-ci.org/bakpakin/janet)
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[](https://ci.appveyor.com/project/bakpakin/janet)
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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 with better utility and performance (arrays, tables, structs, tuples).
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The language also bridging 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 could 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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Implemented in mostly standard C99, janet runs on Windows, Linux and macOS.
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The few features that are not standard C (dynamic library loading, compiler specific optimizations),
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are fairly straight forward. Janet can be easily ported to new platforms.
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For syntax highlighting, there is some preliminary vim syntax highlighting in [janet.vim](https://github.com/bakpakin/janet.vim).
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Generic lisp syntax highlighting should, however, provide good results.
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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. Think Lua or Guile.
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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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* 300+ functions and macros in the core library
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* Interactive environment with detailed stack traces
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## Documentation
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API documentation and design documents can be found in the
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[wiki](https://github.com/bakpakin/janet/wiki). There is an introduction
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section in the wiki that contains a good overview of the language.
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For individual bindings, use the `(doc symbol-name)` macro to get API
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documentation for 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-symbols)` function.
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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-symbols)` into the repl.
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```
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$ ./janet
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Janet 0.0.0 alpha Copyright (C) 2017-2018 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: ./janet [options] scripts...
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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 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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-- Stop handling option
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$
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```
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## Compiling and Running
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Janet only uses Make and batch files to compile on Posix and windows
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respectively. To configure janet, edit the header file src/include/janet/janet.h
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before compilation.
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### Unix-like
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On most platforms, use Make to build janet.
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```sh
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cd somewhere/my/projects/janet
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make
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make test
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```
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After building, run `make install` to install the janet binary and libs.
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Will install in `/usr/local` by default, see the Makefile to customize.
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It's also recommended to set the `JANET_PATH` variable in your profile.
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This is where janet will look for imported libraries after the current directory.
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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` and `gcc` to compile.
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```
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cd somewhere/my/projects/janet
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gmake CC=gcc
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gmake test CC=gcc
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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#)
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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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### Emscripten
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To build janet for the web via [Emscripten](https://kripken.github.io/emscripten-site/), make sure you
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have `emcc` installed and on your path. On a linux or macOS system, use `make janet.js` to build
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`janet.js` and `janet.wasm` - both are needed to run janet in a browser or in node.
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The JavaScript build is what runs the repl on the main website,
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but really serves mainly as a proof of concept. Janet will run much slower in a browser.
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Building with emscripten on windows is currently unsupported.
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## Examples
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See the examples directory for some example janet code.
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## SQLite bindings
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There are some sqlite3 bindings in the directory natives/sqlite3. They serve mostly as a
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proof of concept external c library. To use, first compile the module with Make.
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```sh
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make natives
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```
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Next, enter the repl and create a database and a table.
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```
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janet:1:> (import natives/sqlite3 :as sql)
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nil
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janet:2:> (def db (sql/open "test.db"))
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<sqlite3.connection 0x5561A138C470>
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janet:3:> (sql/eval db `CREATE TABLE customers(id INTEGER PRIMARY KEY, name TEXT);`)
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@[]
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janet:4:> (sql/eval db `INSERT INTO customers VALUES(:id, :name);` {:name "John" :id 12345})
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@[]
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janet:5:> (sql/eval db `SELECT * FROM customers;`)
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@[{"id" 12345 "name" "John"}]
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```
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Finally, close the database connection when done with it.
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```
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janet:6:> (sql/close db)
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nil
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```
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