diff options
Diffstat (limited to 'dhall/src/semantics/nze/normalize.rs')
| -rw-r--r-- | dhall/src/semantics/nze/normalize.rs | 421 |
1 files changed, 421 insertions, 0 deletions
diff --git a/dhall/src/semantics/nze/normalize.rs b/dhall/src/semantics/nze/normalize.rs new file mode 100644 index 0000000..e9d140b --- /dev/null +++ b/dhall/src/semantics/nze/normalize.rs @@ -0,0 +1,421 @@ +use std::collections::HashMap; + +use crate::semantics::NzEnv; +use crate::semantics::{ + Binder, BuiltinClosure, Closure, TextLit, TyExpr, TyExprKind, Value, + ValueKind, +}; +use crate::syntax::{ + BinOp, Builtin, Const, ExprKind, InterpolatedTextContents, +}; +use crate::Normalized; + +pub(crate) fn apply_any(f: Value, a: Value, ty: &Value) -> ValueKind { + match f.kind() { + ValueKind::LamClosure { closure, .. } => { + closure.apply(a).to_whnf_check_type(ty) + } + ValueKind::AppliedBuiltin(closure) => { + closure.apply(a, f.get_type().unwrap(), ty) + } + ValueKind::UnionConstructor(l, kts, uniont) => ValueKind::UnionLit( + l.clone(), + a, + kts.clone(), + uniont.clone(), + f.get_type().unwrap(), + ), + _ => ValueKind::PartialExpr(ExprKind::App(f, a)), + } +} + +pub(crate) fn squash_textlit( + elts: impl Iterator<Item = InterpolatedTextContents<Value>>, +) -> Vec<InterpolatedTextContents<Value>> { + use std::mem::replace; + use InterpolatedTextContents::{Expr, Text}; + + fn inner( + elts: impl Iterator<Item = InterpolatedTextContents<Value>>, + crnt_str: &mut String, + ret: &mut Vec<InterpolatedTextContents<Value>>, + ) { + for contents in elts { + match contents { + Text(s) => crnt_str.push_str(&s), + Expr(e) => match e.kind() { + ValueKind::TextLit(elts2) => { + inner(elts2.iter().cloned(), crnt_str, ret) + } + _ => { + if !crnt_str.is_empty() { + ret.push(Text(replace(crnt_str, String::new()))) + } + ret.push(Expr(e.clone())) + } + }, + } + } + } + + let mut crnt_str = String::new(); + let mut ret = Vec::new(); + inner(elts, &mut crnt_str, &mut ret); + if !crnt_str.is_empty() { + ret.push(Text(replace(&mut crnt_str, String::new()))) + } + ret +} + +pub(crate) fn merge_maps<K, V, F, Err>( + map1: &HashMap<K, V>, + map2: &HashMap<K, V>, + mut f: F, +) -> Result<HashMap<K, V>, Err> +where + F: FnMut(&K, &V, &V) -> Result<V, Err>, + K: std::hash::Hash + Eq + Clone, + V: Clone, +{ + let mut kvs = HashMap::new(); + for (x, v2) in map2 { + let newv = if let Some(v1) = map1.get(x) { + f(x, v1, v2)? + } else { + v2.clone() + }; + kvs.insert(x.clone(), newv); + } + for (x, v1) in map1 { + // Insert only if key not already present + kvs.entry(x.clone()).or_insert_with(|| v1.clone()); + } + Ok(kvs) +} + +// Small helper enum to avoid repetition +enum Ret<'a> { + ValueKind(ValueKind), + Value(Value), + ValueRef(&'a Value), + Expr(ExprKind<Value, Normalized>), +} + +fn apply_binop<'a>( + o: BinOp, + x: &'a Value, + y: &'a Value, + ty: &Value, +) -> Option<Ret<'a>> { + use BinOp::{ + BoolAnd, BoolEQ, BoolNE, BoolOr, Equivalence, ListAppend, NaturalPlus, + NaturalTimes, RecursiveRecordMerge, RecursiveRecordTypeMerge, + RightBiasedRecordMerge, TextAppend, + }; + use ValueKind::{ + BoolLit, EmptyListLit, NEListLit, NaturalLit, RecordLit, RecordType, + }; + Some(match (o, x.kind(), y.kind()) { + (BoolAnd, BoolLit(true), _) => Ret::ValueRef(y), + (BoolAnd, _, BoolLit(true)) => Ret::ValueRef(x), + (BoolAnd, BoolLit(false), _) => Ret::ValueKind(BoolLit(false)), + (BoolAnd, _, BoolLit(false)) => Ret::ValueKind(BoolLit(false)), + (BoolAnd, _, _) if x == y => Ret::ValueRef(x), + (BoolOr, BoolLit(true), _) => Ret::ValueKind(BoolLit(true)), + (BoolOr, _, BoolLit(true)) => Ret::ValueKind(BoolLit(true)), + (BoolOr, BoolLit(false), _) => Ret::ValueRef(y), + (BoolOr, _, BoolLit(false)) => Ret::ValueRef(x), + (BoolOr, _, _) if x == y => Ret::ValueRef(x), + (BoolEQ, BoolLit(true), _) => Ret::ValueRef(y), + (BoolEQ, _, BoolLit(true)) => Ret::ValueRef(x), + (BoolEQ, BoolLit(x), BoolLit(y)) => Ret::ValueKind(BoolLit(x == y)), + (BoolEQ, _, _) if x == y => Ret::ValueKind(BoolLit(true)), + (BoolNE, BoolLit(false), _) => Ret::ValueRef(y), + (BoolNE, _, BoolLit(false)) => Ret::ValueRef(x), + (BoolNE, BoolLit(x), BoolLit(y)) => Ret::ValueKind(BoolLit(x != y)), + (BoolNE, _, _) if x == y => Ret::ValueKind(BoolLit(false)), + + (NaturalPlus, NaturalLit(0), _) => Ret::ValueRef(y), + (NaturalPlus, _, NaturalLit(0)) => Ret::ValueRef(x), + (NaturalPlus, NaturalLit(x), NaturalLit(y)) => { + Ret::ValueKind(NaturalLit(x + y)) + } + (NaturalTimes, NaturalLit(0), _) => Ret::ValueKind(NaturalLit(0)), + (NaturalTimes, _, NaturalLit(0)) => Ret::ValueKind(NaturalLit(0)), + (NaturalTimes, NaturalLit(1), _) => Ret::ValueRef(y), + (NaturalTimes, _, NaturalLit(1)) => Ret::ValueRef(x), + (NaturalTimes, NaturalLit(x), NaturalLit(y)) => { + Ret::ValueKind(NaturalLit(x * y)) + } + + (ListAppend, EmptyListLit(_), _) => Ret::ValueRef(y), + (ListAppend, _, EmptyListLit(_)) => Ret::ValueRef(x), + (ListAppend, NEListLit(xs), NEListLit(ys)) => Ret::ValueKind( + NEListLit(xs.iter().chain(ys.iter()).cloned().collect()), + ), + + (TextAppend, ValueKind::TextLit(x), _) if x.is_empty() => { + Ret::ValueRef(y) + } + (TextAppend, _, ValueKind::TextLit(y)) if y.is_empty() => { + Ret::ValueRef(x) + } + (TextAppend, ValueKind::TextLit(x), ValueKind::TextLit(y)) => { + Ret::ValueKind(ValueKind::TextLit(x.concat(y))) + } + (TextAppend, ValueKind::TextLit(x), _) => Ret::ValueKind( + ValueKind::TextLit(x.concat(&TextLit::interpolate(y.clone()))), + ), + (TextAppend, _, ValueKind::TextLit(y)) => Ret::ValueKind( + ValueKind::TextLit(TextLit::interpolate(x.clone()).concat(y)), + ), + + (RightBiasedRecordMerge, _, RecordLit(kvs)) if kvs.is_empty() => { + Ret::ValueRef(x) + } + (RightBiasedRecordMerge, RecordLit(kvs), _) if kvs.is_empty() => { + Ret::ValueRef(y) + } + (RightBiasedRecordMerge, RecordLit(kvs1), RecordLit(kvs2)) => { + let mut kvs = kvs2.clone(); + for (x, v) in kvs1 { + // Insert only if key not already present + kvs.entry(x.clone()).or_insert_with(|| v.clone()); + } + Ret::ValueKind(RecordLit(kvs)) + } + + (RecursiveRecordMerge, _, RecordLit(kvs)) if kvs.is_empty() => { + Ret::ValueRef(x) + } + (RecursiveRecordMerge, RecordLit(kvs), _) if kvs.is_empty() => { + Ret::ValueRef(y) + } + (RecursiveRecordMerge, RecordLit(kvs1), RecordLit(kvs2)) => { + let kts = match ty.kind() { + RecordType(kts) => kts, + _ => unreachable!("Internal type error"), + }; + let kvs = merge_maps::<_, _, _, !>(kvs1, kvs2, |k, v1, v2| { + Ok(Value::from_partial_expr( + ExprKind::BinOp( + RecursiveRecordMerge, + v1.clone(), + v2.clone(), + ), + kts.get(k).expect("Internal type error").clone(), + )) + })?; + Ret::ValueKind(RecordLit(kvs)) + } + + (RecursiveRecordTypeMerge, RecordType(kts_x), RecordType(kts_y)) => { + let kts = merge_maps::<_, _, _, !>( + kts_x, + kts_y, + // If the Label exists for both records, then we hit the recursive case. + |_, l: &Value, r: &Value| { + Ok(Value::from_partial_expr( + ExprKind::BinOp( + RecursiveRecordTypeMerge, + l.clone(), + r.clone(), + ), + ty.clone(), + )) + }, + )?; + Ret::ValueKind(RecordType(kts)) + } + + (Equivalence, _, _) => { + Ret::ValueKind(ValueKind::Equivalence(x.clone(), y.clone())) + } + + _ => return None, + }) +} + +pub(crate) fn normalize_one_layer( + expr: ExprKind<Value, Normalized>, + ty: &Value, + env: &NzEnv, +) -> ValueKind { + use ValueKind::{ + BoolLit, DoubleLit, EmptyOptionalLit, IntegerLit, NEListLit, + NEOptionalLit, NaturalLit, RecordLit, RecordType, UnionConstructor, + UnionLit, UnionType, + }; + + let ret = match expr { + ExprKind::Import(_) => unreachable!( + "There should remain no imports in a resolved expression" + ), + // Those cases have already been completely handled in the typechecking phase (using + // `RetWhole`), so they won't appear here. + ExprKind::Lam(..) + | ExprKind::Pi(..) + | ExprKind::Let(..) + | ExprKind::Embed(_) + | ExprKind::Var(_) => { + unreachable!("This case should have been handled in typecheck") + } + ExprKind::Annot(x, _) => Ret::Value(x), + ExprKind::Const(c) => Ret::Value(Value::from_const(c)), + ExprKind::Builtin(b) => Ret::Value(Value::from_builtin_env(b, env)), + ExprKind::Assert(_) => Ret::Expr(expr), + ExprKind::App(v, a) => Ret::Value(v.app(a)), + ExprKind::BoolLit(b) => Ret::ValueKind(BoolLit(b)), + ExprKind::NaturalLit(n) => Ret::ValueKind(NaturalLit(n)), + ExprKind::IntegerLit(n) => Ret::ValueKind(IntegerLit(n)), + ExprKind::DoubleLit(n) => Ret::ValueKind(DoubleLit(n)), + ExprKind::SomeLit(e) => Ret::ValueKind(NEOptionalLit(e)), + ExprKind::EmptyListLit(t) => { + let arg = match &*t.kind() { + ValueKind::AppliedBuiltin(BuiltinClosure { + b: Builtin::List, + args, + .. + }) if args.len() == 1 => args[0].clone(), + _ => panic!("internal type error"), + }; + Ret::ValueKind(ValueKind::EmptyListLit(arg)) + } + ExprKind::NEListLit(elts) => { + Ret::ValueKind(NEListLit(elts.into_iter().collect())) + } + ExprKind::RecordLit(kvs) => { + Ret::ValueKind(RecordLit(kvs.into_iter().collect())) + } + ExprKind::RecordType(kvs) => { + Ret::ValueKind(RecordType(kvs.into_iter().collect())) + } + ExprKind::UnionType(kvs) => { + Ret::ValueKind(UnionType(kvs.into_iter().collect())) + } + ExprKind::TextLit(elts) => { + let tlit = TextLit::new(elts.into_iter()); + // Simplify bare interpolation + if let Some(v) = tlit.as_single_expr() { + Ret::Value(v.clone()) + } else { + Ret::ValueKind(ValueKind::TextLit(tlit)) + } + } + ExprKind::BoolIf(ref b, ref e1, ref e2) => { + match b.kind() { + BoolLit(true) => Ret::ValueRef(e1), + BoolLit(false) => Ret::ValueRef(e2), + _ => { + match (e1.kind(), e2.kind()) { + // Simplify `if b then True else False` + (BoolLit(true), BoolLit(false)) => Ret::ValueRef(b), + _ if e1 == e2 => Ret::ValueRef(e1), + _ => Ret::Expr(expr), + } + } + } + } + ExprKind::BinOp(o, ref x, ref y) => match apply_binop(o, x, y, ty) { + Some(ret) => ret, + None => Ret::Expr(expr), + }, + + ExprKind::Projection(_, ref ls) if ls.is_empty() => { + Ret::ValueKind(RecordLit(HashMap::new())) + } + ExprKind::Projection(ref v, ref ls) => match v.kind() { + RecordLit(kvs) => Ret::ValueKind(RecordLit( + ls.iter() + .filter_map(|l| kvs.get(l).map(|x| (l.clone(), x.clone()))) + .collect(), + )), + _ => Ret::Expr(expr), + }, + ExprKind::Field(ref v, ref l) => match v.kind() { + RecordLit(kvs) => match kvs.get(l) { + Some(r) => Ret::Value(r.clone()), + None => Ret::Expr(expr), + }, + UnionType(kts) => Ret::ValueKind(UnionConstructor( + l.clone(), + kts.clone(), + v.get_type().unwrap(), + )), + _ => Ret::Expr(expr), + }, + ExprKind::ProjectionByExpr(_, _) => { + unimplemented!("selection by expression") + } + ExprKind::Completion(_, _) => unimplemented!("record completion"), + + ExprKind::Merge(ref handlers, ref variant, _) => { + match handlers.kind() { + RecordLit(kvs) => match variant.kind() { + UnionConstructor(l, _, _) => match kvs.get(l) { + Some(h) => Ret::Value(h.clone()), + None => Ret::Expr(expr), + }, + UnionLit(l, v, _, _, _) => match kvs.get(l) { + Some(h) => Ret::Value(h.app(v.clone())), + None => Ret::Expr(expr), + }, + EmptyOptionalLit(_) => match kvs.get(&"None".into()) { + Some(h) => Ret::Value(h.clone()), + None => Ret::Expr(expr), + }, + NEOptionalLit(v) => match kvs.get(&"Some".into()) { + Some(h) => Ret::Value(h.app(v.clone())), + None => Ret::Expr(expr), + }, + _ => Ret::Expr(expr), + }, + _ => Ret::Expr(expr), + } + } + ExprKind::ToMap(_, _) => unimplemented!("toMap"), + }; + + match ret { + Ret::ValueKind(v) => v, + Ret::Value(v) => v.to_whnf_check_type(ty), + Ret::ValueRef(v) => v.to_whnf_check_type(ty), + Ret::Expr(expr) => ValueKind::PartialExpr(expr), + } +} + +/// Normalize a TyExpr into WHNF +pub(crate) fn normalize_tyexpr_whnf(tye: &TyExpr, env: &NzEnv) -> ValueKind { + match tye.kind() { + TyExprKind::Var(var) => env.lookup_val(var), + TyExprKind::Expr(ExprKind::Lam(binder, annot, body)) => { + let annot = annot.eval(env); + ValueKind::LamClosure { + binder: Binder::new(binder.clone()), + annot: annot.clone(), + closure: Closure::new(annot, env, body.clone()), + } + } + TyExprKind::Expr(ExprKind::Pi(binder, annot, body)) => { + let annot = annot.eval(env); + let closure = Closure::new(annot.clone(), env, body.clone()); + ValueKind::PiClosure { + binder: Binder::new(binder.clone()), + annot, + closure, + } + } + TyExprKind::Expr(ExprKind::Let(_, None, val, body)) => { + let val = val.eval(env); + body.eval(&env.insert_value(val)).kind().clone() + } + TyExprKind::Expr(e) => { + let ty = match tye.get_type() { + Ok(ty) => ty, + Err(_) => return ValueKind::Const(Const::Sort), + }; + let e = e.map_ref(|tye| tye.eval(env)); + normalize_one_layer(e, &ty, env) + } + } +} |