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blc is an implementation of the binary lambda calculus in Rust.
§Binary lambda calculus basics
Binary lambda calculus (BLC) is a minimal, purely functional programming language based on a binary encoding of the untyped lambda calculus with De Bruijn indices.
Lambda terms have the following representation in BLC:
| term | lambda | BLC |
|---|---|---|
| abstraction | λM | 00M |
| application | MN | 01MN |
| variable | i | 1i0 |
Since BLC programs are basically lambda calculus terms, they can be applied to other terms. In order to be applicable to binary (but not BLC-encoded) input, it has to be lambda-encoded first. Bytestrings are lambda-encoded as Church lists of bytes and bytes are lambda-encoded as Church lists of lambda-encoded bits.
Bits 0 and 1 are lambda-encoded as Church booleans:
| bit | lambda | BLC |
|---|---|---|
| 0 | λλ2 (true) | 0000110 |
| 1 | λλ1 (false) | 000010 |
Example: BLC-encoding steps for a byte representing the ASCII/UTF-8 encoded letter ‘a’:
| encoding | representation |
|---|---|
| decimal | 96 |
| binary | 01100001 |
| lambda | λ1(λλ2)(λ1(λλ1)(λ1(λλ1)(λ1(λλ2)(λ1(λλ2)(λ1(λλ2)(λ1(λλ2)(λ1(λλ1)(λλ1)))))))) |
| BLC (hex) | 16 16 c 2c 10 b0 42 c1 85 83 b 6 16 c 2c 10 41 0 |
Re-exports§
pub use self::execution::run;pub use self::encoding::binary::to_bits;pub use self::encoding::binary::from_bits;