Added a few helper functions for constructing terms
Getty Ritter
10 years ago
| 1 | #![feature(macro_rules)] | |
| 2 | ||
| 1 | 3 | #[deriving(Eq,PartialEq,Clone,Show)] |
| 2 | 4 | enum Term { |
| 3 | 5 | Num(int), |
| 5 | 7 | Lam(String, Box<Term>), |
| 6 | 8 | App(Box<Term>, Box<Term>), |
| 7 | 9 | Let(String, Box<Term>, Box<Term>), |
| 10 | } | |
| 11 | ||
| 12 | fn num(n: int) -> Box<Term> { | |
| 13 | box Num(n) | |
| 14 | } | |
| 15 | ||
| 16 | fn var(s: &str) -> Box<Term> { | |
| 17 | box Var(s.to_string()) | |
| 18 | } | |
| 19 | ||
| 20 | fn lam(x: &str, n: Box<Term>) -> Box<Term> { | |
| 21 | box Lam(x.to_string(), n) | |
| 22 | } | |
| 23 | ||
| 24 | fn app(x: Box<Term>, y: Box<Term>) -> Box<Term> { | |
| 25 | box App(x, y) | |
| 26 | } | |
| 27 | ||
| 28 | fn let_(x: &str, y: Box<Term>, z: Box<Term>) -> Box<Term> { | |
| 29 | box Let(x.to_string(), y, z) | |
| 8 | 30 | } |
| 9 | 31 | |
| 10 | 32 | #[deriving(Eq,PartialEq,Clone,Show)] |
| 59 | 81 | |
| 60 | 82 | fn main() { |
| 61 | 83 | // (λx.λy.x)(5)(6) |
| 62 | let s1 = box App(box App(box Lam("x".to_string(), | |
| 63 | box Lam("y".to_string(), | |
| 64 | box Var("x".to_string()))), | |
| 65 | box Num(5)), | |
| 66 |
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| 84 | let s1 = app(app(lam("x", lam("y", var("x"))), | |
| 85 | num(5)), | |
| 86 | num(6)); | |
| 67 | 87 | // let f = (λx.λy.x)(2) in f 4 |
| 68 | let s2 = box | |
| 69 | Let("f".to_string(), | |
| 70 | box App(box Lam("x".to_string(), | |
| 71 | box Lam("y".to_string(), | |
| 72 | box Var("x".to_string()))), | |
| 73 | box Num(2)), | |
| 74 | box App(box Var("f".to_string()), | |
| 75 | box Num(4)) | |
| 76 |
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| 88 | let s2 = let_("f", | |
| 89 | app(lam("x", lam("y", var("x"))), | |
| 90 | num(2)), | |
| 91 | app(var("f"), | |
| 92 | num(4))); | |
| 77 | 93 | let e = Empty; |
| 78 | 94 | println!("s1: {:}", lcalc_eval(&*s1, &e)); |
| 79 | 95 | println!("s2: {:}", lcalc_eval(&*s2, &e)); |