https://github.com/amake/tinylisp
A very simple Lisp for Java
https://github.com/amake/tinylisp
android java lisp repl scripting
Last synced: about 1 year ago
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A very simple Lisp for Java
- Host: GitHub
- URL: https://github.com/amake/tinylisp
- Owner: amake
- License: apache-2.0
- Created: 2019-01-02T12:58:26.000Z (over 7 years ago)
- Default Branch: master
- Last Pushed: 2023-01-18T00:22:15.000Z (over 3 years ago)
- Last Synced: 2025-03-24T12:39:10.951Z (over 1 year ago)
- Topics: android, java, lisp, repl, scripting
- Language: Java
- Size: 408 KB
- Stars: 7
- Watchers: 3
- Forks: 2
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE.txt
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README
# TinyLisp for Java
TinyLisp is a very simple Lisp implementation for Java. It is heavily inspired
by Peter Norvig's [lis.py](http://norvig.com/lispy.html).
The above demo shows the REPL on Android and illustrates input assist,
auto-formatting, symbol completion, history, and sharing.
## Motivation
Imagine you are working with a proprietary software vendor who provides you with
a native binary compiled for Android. You want to test out the binary, seeing
what kinds of outputs you might get from various inputs.
I was in this position and my first thought was to load it up in a REPL of some
sort. But [JSR
223](https://en.wikipedia.org/wiki/Scripting_for_the_Java_Platform)-compatible
scripting engines did not appear to work on Android, so I decided to make my
own.
Thus the goal of this implementation is to drive a REPL to interact with Java
objects.
## Features
- Basic Lisp things: symbols, lists, strings, numbers, `lambda`, `car`, `cdr`,
`cons`, `list`, `quote`, etc.
- Numbers are parsed as Java `int` or `double`, but are automatically promoted
to `BigDecimal` if necessary when performing arithmetic
- First-class support for Java arrays: `[1 2 3]` is parsed as `int[]`, `[0.1 0.2
0.3]` as `double[]`; mixed or other arrays are `Object[]`
- Java `null`, `true`, `false`
- Android compatibility
## Extras
- [cmd](./cmd):
- A command-line interpreter that can execute files or be a REPL
- A command-line formatter that auto-formats code in an opinionated way
- [formatter](./formatter): The library that powers the formatter
- [activity](./activity): An Android library providing a TinyLisp REPL activity
- [app](./app): An Android app for the activity
## Usage
### Command line
Binaries are available in
[Releases](https://github.com/amake/TinyLisp/releases). Run the appropriate
executable in the `bin` folder.
TinyLisp interpreter:
```sh
$ echo '(+ 1 2 3)' | ./bin/tinylisp
6
$ echo '(+ 1 2 3)' > program.lisp
$ ./bin/tinylisp program.lisp
6
$ ./bin/tinylisp # No args or stdin launches REPL
```
Formatter:
```sh
$ echo "(let ((a 1)(b 2)) (+ a b)'foo)"| ./bin/tlfmt
(let ((a 1)
(b 2))
(+ a b)
'foo)
```
### Engine
The TinyLisp engine is available as a Maven-style dependency:
```
implementation 'org.tinylisp:engine:+'
```
To execute a TinyLisp program, use the `Engine` and `TLEnvironment` classes as
follows. The result is a `TLExpression`.
```java
Engine engine = new Engine();
TLEnvironment env = Engine.defaultEnvironment();
TLExpression result = engine.execute("(+ 1 2 3)", env); // 6
```
### Formatter
The formatter is also available as a package:
```
implementation 'org.tinylisp:formatter:+'
```
### Android REPL activity
The Android REPL activity is also available as a package:
```
implementation 'org.tinylisp:activity:+'
```
The activity class is `org.tinylisp.activity.ReplActivity`.
## Requirements
The engine, formatter, and CLI executables require Java 8+.
The Android REPL activity targets API 32 (min API 15).
## Limitations
- The point is to be small and simple, so many standard commands are missing
(PRs welcome)
- No thought has been put into speed or efficiency
- [Homoiconicity](https://en.wikipedia.org/wiki/Homoiconicity) goes out the
window when printing arbitrary Java objects
## Notes
This TinyLisp is unrelated to any other projects with similar names.