https://github.com/divs1210/impala

Simple, extensible bytecode interpreter
https://github.com/divs1210/impala

bytecode-interpreter clojure vm

Last synced: about 5 hours ago
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Simple, extensible bytecode interpreter

• Host: GitHub
• URL: https://github.com/divs1210/impala
• Owner: divs1210
• License: wtfpl
• Created: 2015-10-10T09:38:03.000Z (about 9 years ago)
• Default Branch: master
• Last Pushed: 2015-10-19T17:14:16.000Z (about 9 years ago)
• Last Synced: 2023-05-12T03:05:16.291Z (over 1 year ago)
• Topics: bytecode-interpreter, clojure, vm
• Language: Clojure
• Size: 160 KB
• Stars: 26
• Watchers: 2
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# Impala

## Simple, extensible bytecode interpreter

Impala is a simple bytecode interpreter written in Clojure.

Written to learn from and to teach making use of.

## Usage

Load everything into namespace.

```clojure

(use '[impala core lib])

```

Write a simple program in impala bytecode and execute it,

printing the whole lifecycle to `stdout`.

```clojure

(let [prog [[SET :a  5]

            [SET :b  3]

            [ADD :a :b]]]

  (run prog true))

```

We can even extend the instruction set by defining our own opcodes

* in Clojure

```clojure

(defn ADD

  "b := b + a"

  [env a b]

  (swap! env update-in [:vars b] + (-> @env :vars a)))

```

or

* __in Impala byte code__!

```clojure

;; from impala.lib

(defop ADD

  "b := b + a"

  [a b] [Z]

  (SUB a Z)

  (SUB Z b))

```

At the heart of this capability is the [SUBLEQ](https://en.wikipedia.org/wiki/One_instruction_set_computer#Subtract_and_branch_if_less_than_or_equal_to_zero) primitive, which is Turing Equivalent.

In this example, `Z` is a temporary register created (and set to 0) every time `ADD` is called, and deleted once it's done executing.

An opcode may use multiple temporary registers.

### Standalone Interpreter

At the terminal, run

```bash

lein uberjar

./impala test/impala/test.imp

```

## License

Impala is licensed under [wtfpl](http://www.wtfpl.net/) and is effectively in the public domain.