mirror of https://github.com/janet-lang/janet
145 lines
5.0 KiB
Markdown
145 lines
5.0 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 can also easily bridge to native code written in C, and supports abstract datatypes
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for interfacing with C. Also support meta programming with macros, and bytecode assembly for the
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janet abstract machine. The bytecode vm is a register based vm loosely inspired by the LuaJIT
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bytecode format, but simpler and safer (bytecode can be verified by the assembler).
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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.
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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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There is not much in the way of documentation yet because it is still a "personal project" and
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I don't want to freeze features prematurely. You can look in the examples directory, the test directory,
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or the file `src/core/core.janet` to get a sense of what janet code looks like.
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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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* First class closures
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* Garbage collection
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* First class green threads (continuations)
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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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* Proper tail calls.
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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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* 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). Not at all complete.
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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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### Posix
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On most platforms, use Make to build janet. To
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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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### 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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## 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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