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//! **blc** is an implementation of the
//! [binary lambda calculus](https://esolangs.org/wiki/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](https://en.wikipedia.org/wiki/Lambda_calculus) with
//! [De Bruijn indices](https://en.wikipedia.org/wiki/De_Bruijn_index).
//!
//! Lambda terms have the following representation in BLC:
//!
//! | term        | lambda | BLC            |
//! --------------|--------|----------------|
//! | abstraction | λM     | 00M            |
//! | application | MN     | 01MN           |
//! | variable    | i      | 1<sup>i</sup>0 |
//!
//! 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](https://en.wikipedia.org/wiki/Church_encoding#One_pair_as_a_list_node) of bytes
//! and bytes are lambda-encoded as Church lists of lambda-encoded bits.
//!
//! Bits 0 and 1 are lambda-encoded as
//! [Church booleans](https://en.wikipedia.org/wiki/Church_encoding#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(<b>λλ2</b>)(λ1(<b>λλ1</b>)(λ1(<b>λλ1</b>)(λ1(<b>λλ2</b>)(λ1(<b>λλ2</b>)(λ1(<b>λλ2</b>)(λ1(<b>λλ2</b>)(λ1(<b>λλ1</b>)(λλ1)))))))) |
//! | BLC (hex) | 16 16 c 2c 10 b0 42 c1 85 83 b 6 16 c 2c 10 41 0 |

#![deny(missing_docs)]

#[macro_use]
extern crate lambda_calculus;

pub use self::execution::run;
pub use self::encoding::binary::{to_bits, from_bits};

pub mod encoding;
pub mod execution;
mod pair_list;