Function lambda_calculus::list::head

pub fn head() -> Term

Equivalent to first(); applied to a Church-encoded list it returns its first element.

HEAD := FIRST

Example

use lambda_calculus::term::Term;
use lambda_calculus::list::head;
use lambda_calculus::arithmetic::{zero, one};
use lambda_calculus::reduction::beta_full;

let list_110 = Term::from(vec![one(), one(), zero()]);

assert_eq!(beta_full(head().app(list_110)), one());