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Merge pull request #728 from tweag/refactor/subst-bound-vars
[Refactor] Remove dead code from subst
This commit is contained in:
Yann Hamdaoui
GitHub
commit
c02539daa7
346
src/eval/mod.rs
346
src/eval/mod.rs
@ -687,204 +687,190 @@ fn update_thunks(stack: &mut Stack, closure: &Closure) {
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/// Recursively substitute each variable occurrence of a term for its value in the environment.
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pub fn subst(rt: RichTerm, global_env: &Environment, env: &Environment) -> RichTerm {
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use std::borrow::Cow;
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use std::collections::HashSet;
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let RichTerm { term, pos } = rt;
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// Maintain an additional set of variables bound by abstractions (`fun x => ..`), that must not
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// be substituted.
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fn subst_(
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rt: RichTerm,
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global_env: &Environment,
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env: &Environment,
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bound: Cow<HashSet<Ident>>,
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) -> RichTerm {
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let RichTerm { term, pos } = rt;
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match term.into_owned() {
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Term::Var(id) if !bound.as_ref().contains(&id) => env
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.get(&id)
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.or_else(|| global_env.get(&id))
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.map(|thunk| {
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let closure = thunk.get_owned();
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subst_(closure.body, global_env, &closure.env, bound)
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match term.into_owned() {
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Term::Var(id) => env
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.get(&id)
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.or_else(|| global_env.get(&id))
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.map(|thunk| {
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let closure = thunk.get_owned();
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subst(closure.body, global_env, &closure.env)
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})
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.unwrap_or_else(|| RichTerm::new(Term::Var(id), pos)),
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v @ Term::Null
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| v @ Term::ParseError
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| v @ Term::Bool(_)
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| v @ Term::Num(_)
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| v @ Term::Str(_)
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// Do not substitute under lambdas: mutually recursive function could cause an infinite
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// loop. Although avoidable, this requires some care and is not currently needed.
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| v @ Term::Fun(..)
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| v @ Term::Lbl(_)
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| v @ Term::Sym(_)
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| v @ Term::Enum(_)
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| v @ Term::Import(_)
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| v @ Term::ResolvedImport(_) => RichTerm::new(v, pos),
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Term::Let(id, t1, t2, attrs) => {
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let t1 = subst(t1, global_env, env);
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let t2 = subst(t2, global_env, env);
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RichTerm::new(Term::Let(id, t1, t2, attrs), pos)
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}
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p @ Term::LetPattern(..) => panic!("Pattern {:?} has not been transformed before evaluation", p),
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p @ Term::FunPattern(..) => panic!("Pattern {:?} has not been transformed before evaluation", p),
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Term::App(t1, t2) => {
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let t1 = subst(t1, global_env, env);
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let t2 = subst(t2, global_env, env);
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RichTerm::new(Term::App(t1, t2), pos)
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}
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Term::Switch(t, cases, default) => {
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let default =
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default.map(|d| subst(d, global_env, env));
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let cases = cases
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.into_iter()
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.map(|(id, t)| {
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(
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id,
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subst(t, global_env, env),
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)
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})
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.unwrap_or_else(|| RichTerm::new(Term::Var(id), pos)),
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v @ Term::Null
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| v @ Term::ParseError
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| v @ Term::Bool(_)
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| v @ Term::Num(_)
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| v @ Term::Str(_)
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// Do not substitute under lambdas: mutually recursive function could cause an infinite
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// loop. Although avoidable, this requires some care and is not currently needed.
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| v @ Term::Fun(..)
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| v @ Term::Lbl(_)
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| v @ Term::Sym(_)
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| v @ Term::Var(_)
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| v @ Term::Enum(_)
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| v @ Term::Import(_)
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| v @ Term::ResolvedImport(_) => RichTerm::new(v, pos),
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Term::Let(id, t1, t2, attrs) => {
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let t1 = subst_(t1, global_env, env, Cow::Borrowed(bound.as_ref()));
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let t2 = subst_(t2, global_env, env, bound);
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.collect();
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let t = subst(t, global_env, env);
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RichTerm::new(Term::Let(id, t1, t2, attrs), pos)
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}
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p @ Term::LetPattern(..) => panic!("Pattern {:?} has not been transformed before evaluation", p),
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p @ Term::FunPattern(..) => panic!("Pattern {:?} has not been transformed before evaluation", p),
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Term::App(t1, t2) => {
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let t1 = subst_(t1, global_env, env, Cow::Borrowed(bound.as_ref()));
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let t2 = subst_(t2, global_env, env, bound);
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RichTerm::new(Term::Switch(t, cases, default), pos)
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}
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Term::Op1(op, t) => {
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let t = subst(t, global_env, env);
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RichTerm::new(Term::App(t1, t2), pos)
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}
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Term::Switch(t, cases, default) => {
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let default =
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default.map(|d| subst_(d, global_env, env, Cow::Borrowed(bound.as_ref())));
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let cases = cases
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.into_iter()
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.map(|(id, t)| {
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(
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id,
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subst_(t, global_env, env, Cow::Borrowed(bound.as_ref())),
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)
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})
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.collect();
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let t = subst_(t, global_env, env, bound);
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RichTerm::new(Term::Op1(op, t), pos)
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}
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Term::Op2(op, t1, t2) => {
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let t1 = subst(t1, global_env, env);
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let t2 = subst(t2, global_env, env);
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RichTerm::new(Term::Switch(t, cases, default), pos)
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}
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Term::Op1(op, t) => {
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let t = subst_(t, global_env, env, bound);
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RichTerm::new(Term::Op2(op, t1, t2), pos)
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}
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Term::OpN(op, ts) => {
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let ts = ts
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.into_iter()
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.map(|t| subst(t, global_env, env))
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.collect();
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RichTerm::new(Term::Op1(op, t), pos)
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}
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Term::Op2(op, t1, t2) => {
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let t1 = subst_(t1, global_env, env, Cow::Borrowed(bound.as_ref()));
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let t2 = subst_(t2, global_env, env, bound);
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RichTerm::new(Term::OpN(op, ts), pos)
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}
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Term::Wrapped(i, t) => {
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let t = subst(t, global_env, env);
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RichTerm::new(Term::Op2(op, t1, t2), pos)
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}
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Term::OpN(op, ts) => {
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let ts = ts
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.into_iter()
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.map(|t| subst_(t, global_env, env, Cow::Borrowed(bound.as_ref())))
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.collect();
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RichTerm::new(Term::Wrapped(i, t), pos)
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}
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Term::Record(map, attrs) => {
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let map = map
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.into_iter()
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.map(|(id, t)| {
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(
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id,
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subst(t, global_env, env),
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)
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})
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.collect();
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RichTerm::new(Term::OpN(op, ts), pos)
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}
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Term::Wrapped(i, t) => {
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let t = subst_(t, global_env, env, bound);
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RichTerm::new(Term::Record(map, attrs), pos)
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}
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Term::RecRecord(map, dyn_fields, attrs, deps) => {
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let map = map
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.into_iter()
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.map(|(id, t)| {
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(
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id,
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subst(t, global_env, env),
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)
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})
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.collect();
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RichTerm::new(Term::Wrapped(i, t), pos)
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}
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Term::Record(map, attrs) => {
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let map = map
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.into_iter()
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.map(|(id, t)| {
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(
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id,
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subst_(t, global_env, env, Cow::Borrowed(bound.as_ref())),
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)
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})
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.collect();
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let dyn_fields = dyn_fields
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.into_iter()
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.map(|(id_t, t)| {
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(
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subst(id_t, global_env, env),
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subst(t, global_env, env),
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)
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})
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.collect();
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RichTerm::new(Term::Record(map, attrs), pos)
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}
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Term::RecRecord(map, dyn_fields, attrs, deps) => {
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let map = map
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.into_iter()
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.map(|(id, t)| {
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(
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id,
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subst_(t, global_env, env, Cow::Borrowed(bound.as_ref())),
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)
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})
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.collect();
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RichTerm::new(Term::RecRecord(map, dyn_fields, attrs, deps), pos)
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}
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Term::Array(ts, attrs) => {
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let ts = ts
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.into_iter()
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.map(|t| subst(t, global_env, env))
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.collect();
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let dyn_fields = dyn_fields
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.into_iter()
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.map(|(id_t, t)| {
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(
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subst_(id_t, global_env, env, Cow::Borrowed(bound.as_ref())),
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subst_(t, global_env, env, Cow::Borrowed(bound.as_ref())),
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)
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})
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.collect();
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RichTerm::new(Term::Array(ts, attrs), pos)
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}
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Term::StrChunks(chunks) => {
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let chunks = chunks
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.into_iter()
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.map(|chunk| match chunk {
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chunk @ StrChunk::Literal(_) => chunk,
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StrChunk::Expr(t, indent) => StrChunk::Expr(
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subst(t, global_env, env),
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indent,
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),
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})
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.collect();
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RichTerm::new(Term::RecRecord(map, dyn_fields, attrs, deps), pos)
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}
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Term::Array(ts, attrs) => {
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let ts = ts
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.into_iter()
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.map(|t| subst_(t, global_env, env, Cow::Borrowed(bound.as_ref())))
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.collect();
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RichTerm::new(Term::StrChunks(chunks), pos)
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}
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Term::MetaValue(meta) => {
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// Currently, there is no interest in replacing variables inside contracts, thus we
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// limit the work of `subst`. If this is needed at some point, just uncomment the
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// following code.
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RichTerm::new(Term::Array(ts, attrs), pos)
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}
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Term::StrChunks(chunks) => {
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let chunks = chunks
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.into_iter()
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.map(|chunk| match chunk {
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chunk @ StrChunk::Literal(_) => chunk,
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StrChunk::Expr(t, indent) => StrChunk::Expr(
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subst_(t, global_env, env, Cow::Borrowed(bound.as_ref())),
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indent,
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),
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})
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.collect();
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// let contracts: Vec<_> = meta
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// .contracts
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// .into_iter()
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// .map(|ctr| {
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// let types = match ctr.types {
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// Types(AbsType::Flat(t)) => Types(AbsType::Flat(subst(
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// t,
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// global_env,
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// env,
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// Cow::Borrowed(bound.as_ref()),
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// ))),
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// ty => ty,
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// };
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//
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// Contract { types, ..ctr }
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// })
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// .collect();
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//
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// let types = meta.types.map(|ctr| {
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// let types = match ctr.types {
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// Types(AbsType::Flat(t)) => Types(AbsType::Flat(subst(
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// t,
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// global_env,
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// env,
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// Cow::Borrowed(bound.as_ref()),
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// ))),
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// ty => ty,
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// };
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//
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// Contract { types, ..ctr }
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// });
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RichTerm::new(Term::StrChunks(chunks), pos)
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}
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Term::MetaValue(meta) => {
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// Currently, there is no interest in replacing variables inside contracts, thus we
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// limit the work of `subst`. If this is needed at some point, just uncomment the
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// following code.
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let value = meta.value.map(|t| subst(t, global_env, env));
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// let contracts: Vec<_> = meta
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// .contracts
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// .into_iter()
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// .map(|ctr| {
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// let types = match ctr.types {
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// Types(AbsType::Flat(t)) => Types(AbsType::Flat(subst_(
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// t,
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// global_env,
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// env,
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// Cow::Borrowed(bound.as_ref()),
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// ))),
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// ty => ty,
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// };
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//
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// Contract { types, ..ctr }
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// })
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// .collect();
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//
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// let types = meta.types.map(|ctr| {
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// let types = match ctr.types {
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// Types(AbsType::Flat(t)) => Types(AbsType::Flat(subst_(
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// t,
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// global_env,
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// env,
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// Cow::Borrowed(bound.as_ref()),
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// ))),
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// ty => ty,
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// };
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//
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// Contract { types, ..ctr }
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// });
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let meta = MetaValue {
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doc: meta.doc,
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value,
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..meta
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};
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let value = meta.value.map(|t| subst_(t, global_env, env, bound));
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let meta = MetaValue {
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doc: meta.doc,
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value,
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..meta
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};
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RichTerm::new(Term::MetaValue(meta), pos)
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}
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RichTerm::new(Term::MetaValue(meta), pos)
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}
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}
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subst_(rt, global_env, env, Cow::Owned(HashSet::new()))
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}
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#[cfg(test)]
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