Half

Half is a minimal functional programming language written in a single C Header file. It's based on untyped lambda-calculus.

Everything is a function. To make Half useful we need to have some impure functions. These functions are called "builtins". There are several builtins:

• :show: send a single bit to the terminal based on the Church booleans it receives (0=false, 1=true).
• :read: return to the program a Church boolean based on the program call arguments or stdin channel (if there is no arguments).
• :ast: (DEBUG ONLY) show the AST of a function.

It means a Half program is a pure function (unless if you introduce non-determenistic builtins yourself!).

In the future I plan to introduce a standard library written in Half itself to avoid doing binary stuff manually for everything.

Examples

Here is a program in Half that output "0" in the terminal:

# zero.hl

1 = \x.\y.x
0 = \x.\y.y

:show 0
:show 0
:show 1
:show 1
:show 0
:show 0
:show 0
:show 0

./half zero.hl
0%

Get started with Half

Use Half as a library

If you want to embed Half in your program you can just copy and paste the header (./libhalf.h) to use in your program! The vast majority of programming languages can import C code through FFI or other methods. You may need yo write a wrapper yourself to expose LibHalf to your language.

Building Half

To build Half you need to have a C compiler supporting C99 installed.

You can just build the main.c with your favourite compiler, and that's all!