Commit b1032f5c3e217497c5c2eb1f1a0824776cf4268a - rust-examples

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lcalc/Cargo.toml less more

	1	[package]
	2
	3	name = "lcalc"
	4	version = "0.0.2"
	5	authors = [ "gdritter@galois.com" ]

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~~lcalc/clean.do~~ less more

1

if [ -e lcalc ]; then rm lcalc; fi

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~~lcalc/default.do~~ less more

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redo-ifchange lcalc

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~~lcalc/lcalc.do~~ less more

1		redo-ifchange lcalc.rs
2		rustc lcalc.rs -o $3

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~~lcalc/lcalc.rs~~ less more

1		#[deriving(Eq,PartialEq,Clone,Show)]
2		enum Term {
3		Num(int),
4		Var(String),
5		Lam(String, Box<Term>),
6		App(Box<Term>, Box<Term>),
7		Let(String, Box<Term>, Box<Term>),
8		}
9
10		#[deriving(Eq,PartialEq,Clone,Show)]
11		enum Val {
12		VNum(int),
13		VLam(String, Box<Term>, Box<Env>),
14		}
15
16		#[deriving(Eq,PartialEq,Clone,Show)]
17		enum Env {
18		Empty,
19		Binding(String, Box<Val>, Box<Env>),
20		}
21
22		fn lookup(s: &String, e: &Env) -> Box<Val> {
23		match *e {
24		Empty => { fail!(format!("Couldn't find {} in environment", s)) }
25		Binding(ref n, ref v, ref p) => {
26		if n == s {
27		v.clone()
28		} else {
29		lookup(s, &**p)
30		}
31		}
32		}
33		}
34
35		fn lcalc_eval(t: &Term, e: &Env) -> Box<Val> {
36		match t {
37		&Num(num) => { box VNum(num) }
38		&Var(ref str) => { lookup(str, e) }
39		&Lam(ref s, ref b) => { box VLam(s.clone(), b.clone(), box e.clone()) }
40		&App(box ref f, box ref x) => {
41		match *lcalc_eval(f, e) {
42		VLam(ref arg, box ref body, box ref env) => {
43		let newEnv = Binding(arg.clone(),
44		lcalc_eval(x, e),
45		box env.clone());
46		lcalc_eval(body, &newEnv)
47		}
48		_ => fail!()
49		}
50		}
51		&Let(ref s, box ref t, box ref b) => {
52		let newEnv = Binding(s.clone(),
53		lcalc_eval(t, e),
54		box e.clone());
55		lcalc_eval(b, &newEnv)
56		}
57		}
58		}
59
60		fn main() {
61		// (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		box Num(8));
67		// 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		);
77		let e = Empty;
78		println!("s1: {:}", lcalc_eval(&*s1, &e));
79		println!("s2: {:}", lcalc_eval(&*s2, &e));
80		}

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lcalc/src/main.rs less more

	1	#[deriving(Eq,PartialEq,Clone,Show)]
	2	enum Term {
	3	Num(int),
	4	Var(String),
	5	Lam(String, Box<Term>),
	6	App(Box<Term>, Box<Term>),
	7	Let(String, Box<Term>, Box<Term>),
	8	}
	9
	10	#[deriving(Eq,PartialEq,Clone,Show)]
	11	enum Val {
	12	VNum(int),
	13	VLam(String, Box<Term>, Box<Env>),
	14	}
	15
	16	#[deriving(Eq,PartialEq,Clone,Show)]
	17	enum Env {
	18	Empty,
	19	Binding(String, Box<Val>, Box<Env>),
	20	}
	21
	22	fn lookup(s: &String, e: &Env) -> Box<Val> {
	23	match *e {
	24	Empty => { fail!(format!("Couldn't find {} in environment", s)) }
	25	Binding(ref n, ref v, ref p) => {
	26	if n == s {
	27	v.clone()
	28	} else {
	29	lookup(s, &**p)
	30	}
	31	}
	32	}
	33	}
	34
	35	fn lcalc_eval(t: &Term, e: &Env) -> Box<Val> {
	36	match t {
	37	&Num(num) => { box VNum(num) }
	38	&Var(ref str) => { lookup(str, e) }
	39	&Lam(ref s, ref b) => { box VLam(s.clone(), b.clone(), box e.clone()) }
	40	&App(box ref f, box ref x) => {
	41	match *lcalc_eval(f, e) {
	42	VLam(ref arg, box ref body, box ref env) => {
	43	let newEnv = Binding(arg.clone(),
	44	lcalc_eval(x, e),
	45	box env.clone());
	46	lcalc_eval(body, &newEnv)
	47	}
	48	_ => fail!()
	49	}
	50	}
	51	&Let(ref s, box ref t, box ref b) => {
	52	let newEnv = Binding(s.clone(),
	53	lcalc_eval(t, e),
	54	box e.clone());
	55	lcalc_eval(b, &newEnv)
	56	}
	57	}
	58	}
	59
	60	fn main() {
	61	// (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	box Num(8));
	67	// 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	);
	77	let e = Empty;
	78	println!("s1: {:}", lcalc_eval(&*s1, &e));
	79	println!("s2: {:}", lcalc_eval(&*s2, &e));
	80	}