Jffy Lang

JFF Programming Language

Pronounced however you'd like; some suggestions: "Jeffy lang", "Jiffy lang"

Latest Version: 0.1.0-prealpha

DISCLAIMER: This is not a production level lanugage, use at your own risk!

This language is written expressly following Robert Nystrom's Book: Crafting Interpreters I may make changes, if there is something I feel like implementing beyond what is in the book. Those may or may not be well documented.

The book recommends following along in Java to write the interpreter, or refer to other people's interpretations in the language of your choice. I'm doing neither as I want to challenge myself.

The interpreter and initial compiler will be written in Go, later the intention is to (maybe) rewrite both in Jffy.

This language is being made Just For Fun, it is released under the MIT Licence.

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Usage

There is no build provided currently. You will need to build from scratch.

Equally, there aren't any sugary things like LSPs, formatters, or the like, you won't have any fancy colouring when writing code in Jffy just yet.

Building

1. Clone this repo
2. Make sure you have Go installed
3. Run make

You now have a build of Jffy in the ./bin folder.

Running

REPL

Simply calling ./bin/jffy will start the REPL.

NOTE: The REPL needs a bit of work doing to make it nicer to work with.

Files

Write your code in a file, use the extensions .jff or .jffy, whichever takes your fancy.

Call ./bin/jffy yourfile.jff

NOTE: Currently only a single file is supported.

Syntax

Variables

var a;
var b = "some string";

print a; // error

a = 1;
print a; // 1; ok

Printing

var a = "hello";
print a; // hello

Concatenation

var a = "hello ";
print a .. "world"; // hello world

Maths

print 2 + 3; // 5
print 3 - 2; // 1
print 2 * 3; // 6
print 6 / 3; // 2

print 2 < 3; // true
print 2 > 3; // false
print 2 <= 2; // true
print 3 >= 5; // false

Control Flow

var a = 5;
if a == 5 {
    print "a is what it is";
} else {
    print "I should never see the light of day!";
}

var i = 0;
while i < 10 {
    print i; // 0..9
    i = i + 1;
}

for var i = 0; i < 10; i = i + 1 {
    print i; // 0..9
}

Functions

fun add(a, b) {
    return a + b;
}

print add(1, 2); // 3

Anonymous Functions

fun add(a, b, fn) {
    fn(a + b);
}

add(2, 5, fun (total) {
    print total;
}); // 7

var a = fun (total) {
    print total * 10;
}

add(2, 3, a); // 50

Documentation

Docs
Design
Todo
Changelog