ivanallen/autumn

An interpreter to learn

Autumn

An easy interpreter to learn.

Features

• Modern C++ style(Based on C++17)
• Support Linux and MacOS
• Full comments
• Support debug in repl

• Higher-order functions supported

• Closure supported

• ...

Quick Start

Install GCC8

• Centos

$ yum install readline-devel.x86_64
$ yum install -y devtoolset-8-toolchain
$ scl enable devtoolset-8 bash

• Ubuntu

$ sudo add-apt-repository -y ppa:ubuntu-toolchain-r/test
$ sudo apt-get update -qq
$ sudo apt-get install -qq g++-8
$ apt-get install lib64readline-dev
$ export CXX="g++-8"
$ export CC="gcc-8"

Build & Test

$ make

Repl

• lexer mode

$ ./autumn lexer

• parser mode

$ ./autumn parser

• debug in parser mode

$ DEBUG_AUTUMN=1 ./autumn parser

• eval mode

$ ./autumn eval

Demo

An example below showing how to write quick sort.

• You need a filter function

let filter = fn(arr, f) {
    let iter = fn(arr, accumulated) {
        if (len(arr) == 0) {
            accumulated
        } else {
            let e = if (f(first(arr))) {
                push(accumulated, first(arr));
            } else {
                accumulated
            }
            iter(rest(arr), e);
        }
    };
    iter(arr, []);
};

• QuickSort

let quickSort = fn(arr) {
    if (len(arr) == 0) {
        return arr;
    } else {
        let head = first(arr);
        let smaller = filter(rest(arr), fn(x) { x <= head });
        let bigger = filter(rest(arr), fn(x) { x > head });
        return quickSort(smaller) + [head] + quickSort(bigger);
    }
}

let a = [4,5,3,4,6,6]
quickSort(a)

Contributor

Allen.

License

This project maintained under BSD 2.

Contact

QQ Group for Autumn: 985682510 QQ Group for Linuxers: 610441700

References

• Write An Interpreter In Go