From 7abd49772643ee4e131ef47de66db22ba7c1e037 Mon Sep 17 00:00:00 2001 From: Nadrieril Date: Sun, 15 Dec 2019 19:47:20 +0000 Subject: Move contents of dhall under a semantics submodule --- dhall/src/semantics/phase/normalize.rs | 794 +++++++++++++++++++++++++++++++++ 1 file changed, 794 insertions(+) create mode 100644 dhall/src/semantics/phase/normalize.rs (limited to 'dhall/src/semantics/phase/normalize.rs') diff --git a/dhall/src/semantics/phase/normalize.rs b/dhall/src/semantics/phase/normalize.rs new file mode 100644 index 0000000..3ed53f4 --- /dev/null +++ b/dhall/src/semantics/phase/normalize.rs @@ -0,0 +1,794 @@ +use std::collections::HashMap; + +use crate::syntax::Const::Type; +use crate::syntax::{ + BinOp, Builtin, ExprF, InterpolatedText, InterpolatedTextContents, Label, + NaiveDouble, +}; + +use crate::core::value::Value; +use crate::core::valuef::ValueF; +use crate::core::var::{AlphaLabel, Shift, Subst}; +use crate::phase::Normalized; + +// Ad-hoc macro to help construct closures +macro_rules! make_closure { + (#$var:ident) => { $var.clone() }; + (var($var:ident, $n:expr, $($ty:tt)*)) => {{ + let var = crate::core::var::AlphaVar::from_var_and_alpha( + Label::from(stringify!($var)).into(), + $n + ); + ValueF::Var(var) + .into_value_with_type(make_closure!($($ty)*)) + }}; + // Warning: assumes that $ty, as a dhall value, has type `Type` + (λ($var:ident : $($ty:tt)*) -> $($body:tt)*) => {{ + let var: AlphaLabel = Label::from(stringify!($var)).into(); + let ty = make_closure!($($ty)*); + let body = make_closure!($($body)*); + let body_ty = body.get_type_not_sort(); + let lam_ty = ValueF::Pi(var.clone(), ty.clone(), body_ty) + .into_value_with_type(Value::from_const(Type)); + ValueF::Lam(var, ty, body).into_value_with_type(lam_ty) + }}; + (Natural) => { + Value::from_builtin(Builtin::Natural) + }; + (List $($rest:tt)*) => { + Value::from_builtin(Builtin::List) + .app(make_closure!($($rest)*)) + }; + (Some($($rest:tt)*)) => {{ + let v = make_closure!($($rest)*); + let v_type = v.get_type_not_sort(); + let opt_v_type = Value::from_builtin(Builtin::Optional).app(v_type); + ValueF::NEOptionalLit(v).into_value_with_type(opt_v_type) + }}; + (1 + $($rest:tt)*) => { + ValueF::PartialExpr(ExprF::BinOp( + crate::syntax::BinOp::NaturalPlus, + make_closure!($($rest)*), + Value::from_valuef_and_type( + ValueF::NaturalLit(1), + make_closure!(Natural) + ), + )).into_value_with_type( + make_closure!(Natural) + ) + }; + ([ $($head:tt)* ] # $($tail:tt)*) => {{ + let head = make_closure!($($head)*); + let tail = make_closure!($($tail)*); + let list_type = tail.get_type_not_sort(); + ValueF::PartialExpr(ExprF::BinOp( + crate::syntax::BinOp::ListAppend, + ValueF::NEListLit(vec![head]) + .into_value_with_type(list_type.clone()), + tail, + )).into_value_with_type(list_type) + }}; +} + +#[allow(clippy::cognitive_complexity)] +pub(crate) fn apply_builtin( + b: Builtin, + args: Vec, + ty: &Value, +) -> ValueF { + use crate::syntax::Builtin::*; + use ValueF::*; + + // Small helper enum + enum Ret<'a> { + ValueF(ValueF), + Value(Value), + // For applications that can return a function, it's important to keep the remaining + // arguments to apply them to the resulting function. + ValueWithRemainingArgs(&'a [Value], Value), + DoneAsIs, + } + + let ret = match (b, args.as_slice()) { + (OptionalNone, [t]) => Ret::ValueF(EmptyOptionalLit(t.clone())), + (NaturalIsZero, [n]) => match &*n.as_whnf() { + NaturalLit(n) => Ret::ValueF(BoolLit(*n == 0)), + _ => Ret::DoneAsIs, + }, + (NaturalEven, [n]) => match &*n.as_whnf() { + NaturalLit(n) => Ret::ValueF(BoolLit(*n % 2 == 0)), + _ => Ret::DoneAsIs, + }, + (NaturalOdd, [n]) => match &*n.as_whnf() { + NaturalLit(n) => Ret::ValueF(BoolLit(*n % 2 != 0)), + _ => Ret::DoneAsIs, + }, + (NaturalToInteger, [n]) => match &*n.as_whnf() { + NaturalLit(n) => Ret::ValueF(IntegerLit(*n as isize)), + _ => Ret::DoneAsIs, + }, + (NaturalShow, [n]) => match &*n.as_whnf() { + NaturalLit(n) => { + Ret::ValueF(TextLit(vec![InterpolatedTextContents::Text( + n.to_string(), + )])) + } + _ => Ret::DoneAsIs, + }, + (NaturalSubtract, [a, b]) => match (&*a.as_whnf(), &*b.as_whnf()) { + (NaturalLit(a), NaturalLit(b)) => { + Ret::ValueF(NaturalLit(if b > a { b - a } else { 0 })) + } + (NaturalLit(0), _) => Ret::Value(b.clone()), + (_, NaturalLit(0)) => Ret::ValueF(NaturalLit(0)), + _ if a == b => Ret::ValueF(NaturalLit(0)), + _ => Ret::DoneAsIs, + }, + (IntegerShow, [n]) => match &*n.as_whnf() { + IntegerLit(n) => { + let s = if *n < 0 { + n.to_string() + } else { + format!("+{}", n) + }; + Ret::ValueF(TextLit(vec![InterpolatedTextContents::Text(s)])) + } + _ => Ret::DoneAsIs, + }, + (IntegerToDouble, [n]) => match &*n.as_whnf() { + IntegerLit(n) => { + Ret::ValueF(DoubleLit(NaiveDouble::from(*n as f64))) + } + _ => Ret::DoneAsIs, + }, + (DoubleShow, [n]) => match &*n.as_whnf() { + DoubleLit(n) => { + Ret::ValueF(TextLit(vec![InterpolatedTextContents::Text( + n.to_string(), + )])) + } + _ => Ret::DoneAsIs, + }, + (TextShow, [v]) => match &*v.as_whnf() { + TextLit(elts) => { + match elts.as_slice() { + // Empty string literal. + [] => { + // Printing InterpolatedText takes care of all the escaping + let txt: InterpolatedText = + std::iter::empty().collect(); + let s = txt.to_string(); + Ret::ValueF(TextLit(vec![ + InterpolatedTextContents::Text(s), + ])) + } + // If there are no interpolations (invariants ensure that when there are no + // interpolations, there is a single Text item) in the literal. + [InterpolatedTextContents::Text(s)] => { + // Printing InterpolatedText takes care of all the escaping + let txt: InterpolatedText = + std::iter::once(InterpolatedTextContents::Text( + s.clone(), + )) + .collect(); + let s = txt.to_string(); + Ret::ValueF(TextLit(vec![ + InterpolatedTextContents::Text(s), + ])) + } + _ => Ret::DoneAsIs, + } + } + _ => Ret::DoneAsIs, + }, + (ListLength, [_, l]) => match &*l.as_whnf() { + EmptyListLit(_) => Ret::ValueF(NaturalLit(0)), + NEListLit(xs) => Ret::ValueF(NaturalLit(xs.len())), + _ => Ret::DoneAsIs, + }, + (ListHead, [_, l]) => match &*l.as_whnf() { + EmptyListLit(n) => Ret::ValueF(EmptyOptionalLit(n.clone())), + NEListLit(xs) => { + Ret::ValueF(NEOptionalLit(xs.iter().next().unwrap().clone())) + } + _ => Ret::DoneAsIs, + }, + (ListLast, [_, l]) => match &*l.as_whnf() { + EmptyListLit(n) => Ret::ValueF(EmptyOptionalLit(n.clone())), + NEListLit(xs) => Ret::ValueF(NEOptionalLit( + xs.iter().rev().next().unwrap().clone(), + )), + _ => Ret::DoneAsIs, + }, + (ListReverse, [_, l]) => match &*l.as_whnf() { + EmptyListLit(n) => Ret::ValueF(EmptyListLit(n.clone())), + NEListLit(xs) => { + Ret::ValueF(NEListLit(xs.iter().rev().cloned().collect())) + } + _ => Ret::DoneAsIs, + }, + (ListIndexed, [_, l]) => { + let l_whnf = l.as_whnf(); + match &*l_whnf { + EmptyListLit(_) | NEListLit(_) => { + // Extract the type of the list elements + let t = match &*l_whnf { + EmptyListLit(t) => t.clone(), + NEListLit(xs) => xs[0].get_type_not_sort(), + _ => unreachable!(), + }; + + // Construct the returned record type: { index: Natural, value: t } + let mut kts = HashMap::new(); + kts.insert("index".into(), Value::from_builtin(Natural)); + kts.insert("value".into(), t.clone()); + let t = Value::from_valuef_and_type( + RecordType(kts), + Value::from_const(Type), + ); + + // Construct the new list, with added indices + let list = match &*l_whnf { + EmptyListLit(_) => EmptyListLit(t), + NEListLit(xs) => NEListLit( + xs.iter() + .enumerate() + .map(|(i, e)| { + let mut kvs = HashMap::new(); + kvs.insert( + "index".into(), + Value::from_valuef_and_type( + NaturalLit(i), + Value::from_builtin( + Builtin::Natural, + ), + ), + ); + kvs.insert("value".into(), e.clone()); + Value::from_valuef_and_type( + RecordLit(kvs), + t.clone(), + ) + }) + .collect(), + ), + _ => unreachable!(), + }; + Ret::ValueF(list) + } + _ => Ret::DoneAsIs, + } + } + (ListBuild, [t, f]) => match &*f.as_whnf() { + // fold/build fusion + ValueF::AppliedBuiltin(ListFold, args) => { + if args.len() >= 2 { + Ret::Value(args[1].clone()) + } else { + // Do we really need to handle this case ? + unimplemented!() + } + } + _ => { + let list_t = Value::from_builtin(List).app(t.clone()); + Ret::Value( + f.app(list_t.clone()) + .app({ + // Move `t` under new variables + let t1 = t.under_binder(Label::from("x")); + let t2 = t1.under_binder(Label::from("xs")); + make_closure!( + λ(x : #t) -> + λ(xs : List #t1) -> + [ var(x, 1, #t2) ] # var(xs, 0, List #t2) + ) + }) + .app( + EmptyListLit(t.clone()) + .into_value_with_type(list_t), + ), + ) + } + }, + (ListFold, [_, l, _, cons, nil, r @ ..]) => match &*l.as_whnf() { + EmptyListLit(_) => Ret::ValueWithRemainingArgs(r, nil.clone()), + NEListLit(xs) => { + let mut v = nil.clone(); + for x in xs.iter().cloned().rev() { + v = cons.app(x).app(v); + } + Ret::ValueWithRemainingArgs(r, v) + } + _ => Ret::DoneAsIs, + }, + (OptionalBuild, [t, f]) => match &*f.as_whnf() { + // fold/build fusion + ValueF::AppliedBuiltin(OptionalFold, args) => { + if args.len() >= 2 { + Ret::Value(args[1].clone()) + } else { + // Do we really need to handle this case ? + unimplemented!() + } + } + _ => { + let optional_t = Value::from_builtin(Optional).app(t.clone()); + Ret::Value( + f.app(optional_t.clone()) + .app({ + let t1 = t.under_binder(Label::from("x")); + make_closure!(λ(x: #t) -> Some(var(x, 0, #t1))) + }) + .app( + EmptyOptionalLit(t.clone()) + .into_value_with_type(optional_t), + ), + ) + } + }, + (OptionalFold, [_, v, _, just, nothing, r @ ..]) => match &*v.as_whnf() + { + EmptyOptionalLit(_) => { + Ret::ValueWithRemainingArgs(r, nothing.clone()) + } + NEOptionalLit(x) => { + Ret::ValueWithRemainingArgs(r, just.app(x.clone())) + } + _ => Ret::DoneAsIs, + }, + (NaturalBuild, [f]) => match &*f.as_whnf() { + // fold/build fusion + ValueF::AppliedBuiltin(NaturalFold, args) => { + if !args.is_empty() { + Ret::Value(args[0].clone()) + } else { + // Do we really need to handle this case ? + unimplemented!() + } + } + _ => Ret::Value( + f.app(Value::from_builtin(Natural)) + .app(make_closure!( + λ(x : Natural) -> 1 + var(x, 0, Natural) + )) + .app( + NaturalLit(0) + .into_value_with_type(Value::from_builtin(Natural)), + ), + ), + }, + (NaturalFold, [n, t, succ, zero, r @ ..]) => match &*n.as_whnf() { + NaturalLit(0) => Ret::ValueWithRemainingArgs(r, zero.clone()), + NaturalLit(n) => { + let fold = Value::from_builtin(NaturalFold) + .app( + NaturalLit(n - 1) + .into_value_with_type(Value::from_builtin(Natural)), + ) + .app(t.clone()) + .app(succ.clone()) + .app(zero.clone()); + Ret::ValueWithRemainingArgs(r, succ.app(fold)) + } + _ => Ret::DoneAsIs, + }, + _ => Ret::DoneAsIs, + }; + match ret { + Ret::ValueF(v) => v, + Ret::Value(v) => v.to_whnf_check_type(ty), + Ret::ValueWithRemainingArgs(unconsumed_args, mut v) => { + let n_consumed_args = args.len() - unconsumed_args.len(); + for x in args.into_iter().skip(n_consumed_args) { + v = v.app(x); + } + v.to_whnf_check_type(ty) + } + Ret::DoneAsIs => AppliedBuiltin(b, args), + } +} + +pub(crate) fn apply_any(f: Value, a: Value, ty: &Value) -> ValueF { + let f_borrow = f.as_whnf(); + match &*f_borrow { + ValueF::Lam(x, _, e) => { + e.subst_shift(&x.into(), &a).to_whnf_check_type(ty) + } + ValueF::AppliedBuiltin(b, args) => { + use std::iter::once; + let args = args.iter().cloned().chain(once(a.clone())).collect(); + apply_builtin(*b, args, ty) + } + ValueF::UnionConstructor(l, kts) => { + ValueF::UnionLit(l.clone(), a, kts.clone()) + } + _ => { + drop(f_borrow); + ValueF::PartialExpr(ExprF::App(f, a)) + } + } +} + +pub(crate) fn squash_textlit( + elts: impl Iterator>, +) -> Vec> { + use std::mem::replace; + use InterpolatedTextContents::{Expr, Text}; + + fn inner( + elts: impl Iterator>, + crnt_str: &mut String, + ret: &mut Vec>, + ) { + for contents in elts { + match contents { + Text(s) => crnt_str.push_str(&s), + Expr(e) => { + let e_borrow = e.as_whnf(); + match &*e_borrow { + ValueF::TextLit(elts2) => { + inner(elts2.iter().cloned(), crnt_str, ret) + } + _ => { + drop(e_borrow); + 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( + map1: &HashMap, + map2: &HashMap, + mut f: F, +) -> Result, Err> +where + F: FnMut(&K, &V, &V) -> Result, + 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> { + ValueF(ValueF), + Value(Value), + ValueRef(&'a Value), + Expr(ExprF), +} + +fn apply_binop<'a>( + o: BinOp, + x: &'a Value, + y: &'a Value, + ty: &Value, +) -> Option> { + use BinOp::{ + BoolAnd, BoolEQ, BoolNE, BoolOr, Equivalence, ListAppend, NaturalPlus, + NaturalTimes, RecursiveRecordMerge, RecursiveRecordTypeMerge, + RightBiasedRecordMerge, TextAppend, + }; + use ValueF::{ + BoolLit, EmptyListLit, NEListLit, NaturalLit, RecordLit, RecordType, + TextLit, + }; + let x_borrow = x.as_whnf(); + let y_borrow = y.as_whnf(); + Some(match (o, &*x_borrow, &*y_borrow) { + (BoolAnd, BoolLit(true), _) => Ret::ValueRef(y), + (BoolAnd, _, BoolLit(true)) => Ret::ValueRef(x), + (BoolAnd, BoolLit(false), _) => Ret::ValueF(BoolLit(false)), + (BoolAnd, _, BoolLit(false)) => Ret::ValueF(BoolLit(false)), + (BoolAnd, _, _) if x == y => Ret::ValueRef(x), + (BoolOr, BoolLit(true), _) => Ret::ValueF(BoolLit(true)), + (BoolOr, _, BoolLit(true)) => Ret::ValueF(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::ValueF(BoolLit(x == y)), + (BoolEQ, _, _) if x == y => Ret::ValueF(BoolLit(true)), + (BoolNE, BoolLit(false), _) => Ret::ValueRef(y), + (BoolNE, _, BoolLit(false)) => Ret::ValueRef(x), + (BoolNE, BoolLit(x), BoolLit(y)) => Ret::ValueF(BoolLit(x != y)), + (BoolNE, _, _) if x == y => Ret::ValueF(BoolLit(false)), + + (NaturalPlus, NaturalLit(0), _) => Ret::ValueRef(y), + (NaturalPlus, _, NaturalLit(0)) => Ret::ValueRef(x), + (NaturalPlus, NaturalLit(x), NaturalLit(y)) => { + Ret::ValueF(NaturalLit(x + y)) + } + (NaturalTimes, NaturalLit(0), _) => Ret::ValueF(NaturalLit(0)), + (NaturalTimes, _, NaturalLit(0)) => Ret::ValueF(NaturalLit(0)), + (NaturalTimes, NaturalLit(1), _) => Ret::ValueRef(y), + (NaturalTimes, _, NaturalLit(1)) => Ret::ValueRef(x), + (NaturalTimes, NaturalLit(x), NaturalLit(y)) => { + Ret::ValueF(NaturalLit(x * y)) + } + + (ListAppend, EmptyListLit(_), _) => Ret::ValueRef(y), + (ListAppend, _, EmptyListLit(_)) => Ret::ValueRef(x), + (ListAppend, NEListLit(xs), NEListLit(ys)) => Ret::ValueF(NEListLit( + xs.iter().chain(ys.iter()).cloned().collect(), + )), + + (TextAppend, TextLit(x), _) if x.is_empty() => Ret::ValueRef(y), + (TextAppend, _, TextLit(y)) if y.is_empty() => Ret::ValueRef(x), + (TextAppend, TextLit(x), TextLit(y)) => Ret::ValueF(TextLit( + squash_textlit(x.iter().chain(y.iter()).cloned()), + )), + (TextAppend, TextLit(x), _) => { + use std::iter::once; + let y = InterpolatedTextContents::Expr(y.clone()); + Ret::ValueF(TextLit(squash_textlit( + x.iter().cloned().chain(once(y)), + ))) + } + (TextAppend, _, TextLit(y)) => { + use std::iter::once; + let x = InterpolatedTextContents::Expr(x.clone()); + Ret::ValueF(TextLit(squash_textlit( + once(x).chain(y.iter().cloned()), + ))) + } + + (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::ValueF(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 ty_borrow = ty.as_whnf(); + let kts = match &*ty_borrow { + RecordType(kts) => kts, + _ => unreachable!("Internal type error"), + }; + let kvs = merge_maps::<_, _, _, !>(kvs1, kvs2, |k, v1, v2| { + Ok(Value::from_valuef_and_type( + ValueF::PartialExpr(ExprF::BinOp( + RecursiveRecordMerge, + v1.clone(), + v2.clone(), + )), + kts.get(k).expect("Internal type error").clone(), + )) + })?; + Ret::ValueF(RecordLit(kvs)) + } + + (RecursiveRecordTypeMerge, _, _) | (Equivalence, _, _) => { + unreachable!("This case should have been handled in typecheck") + } + + _ => return None, + }) +} + +pub(crate) fn normalize_one_layer( + expr: ExprF, + ty: &Value, +) -> ValueF { + use ValueF::{ + AppliedBuiltin, BoolLit, DoubleLit, EmptyListLit, IntegerLit, + NEListLit, NEOptionalLit, NaturalLit, RecordLit, TextLit, + UnionConstructor, UnionLit, UnionType, + }; + + let ret = match expr { + ExprF::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. + ExprF::Lam(_, _, _) + | ExprF::Pi(_, _, _) + | ExprF::Let(_, _, _, _) + | ExprF::Embed(_) + | ExprF::Const(_) + | ExprF::Builtin(_) + | ExprF::Var(_) + | ExprF::Annot(_, _) + | ExprF::RecordType(_) + | ExprF::UnionType(_) => { + unreachable!("This case should have been handled in typecheck") + } + ExprF::Assert(_) => Ret::Expr(expr), + ExprF::App(v, a) => Ret::Value(v.app(a)), + ExprF::BoolLit(b) => Ret::ValueF(BoolLit(b)), + ExprF::NaturalLit(n) => Ret::ValueF(NaturalLit(n)), + ExprF::IntegerLit(n) => Ret::ValueF(IntegerLit(n)), + ExprF::DoubleLit(n) => Ret::ValueF(DoubleLit(n)), + ExprF::SomeLit(e) => Ret::ValueF(NEOptionalLit(e)), + ExprF::EmptyListLit(ref t) => { + // Check if the type is of the form `List x` + let t_borrow = t.as_whnf(); + match &*t_borrow { + AppliedBuiltin(Builtin::List, args) if args.len() == 1 => { + Ret::ValueF(EmptyListLit(args[0].clone())) + } + _ => { + drop(t_borrow); + Ret::Expr(expr) + } + } + } + ExprF::NEListLit(elts) => { + Ret::ValueF(NEListLit(elts.into_iter().collect())) + } + ExprF::RecordLit(kvs) => { + Ret::ValueF(RecordLit(kvs.into_iter().collect())) + } + ExprF::TextLit(elts) => { + use InterpolatedTextContents::Expr; + let elts: Vec<_> = squash_textlit(elts.into_iter()); + // Simplify bare interpolation + if let [Expr(th)] = elts.as_slice() { + Ret::Value(th.clone()) + } else { + Ret::ValueF(TextLit(elts)) + } + } + ExprF::BoolIf(ref b, ref e1, ref e2) => { + let b_borrow = b.as_whnf(); + match &*b_borrow { + BoolLit(true) => Ret::ValueRef(e1), + BoolLit(false) => Ret::ValueRef(e2), + _ => { + let e1_borrow = e1.as_whnf(); + let e2_borrow = e2.as_whnf(); + match (&*e1_borrow, &*e2_borrow) { + // Simplify `if b then True else False` + (BoolLit(true), BoolLit(false)) => Ret::ValueRef(b), + _ if e1 == e2 => Ret::ValueRef(e1), + _ => { + drop(b_borrow); + drop(e1_borrow); + drop(e2_borrow); + Ret::Expr(expr) + } + } + } + } + } + ExprF::BinOp(o, ref x, ref y) => match apply_binop(o, x, y, ty) { + Some(ret) => ret, + None => Ret::Expr(expr), + }, + + ExprF::Projection(_, ref ls) if ls.is_empty() => { + Ret::ValueF(RecordLit(HashMap::new())) + } + ExprF::Projection(ref v, ref ls) => { + let v_borrow = v.as_whnf(); + match &*v_borrow { + RecordLit(kvs) => Ret::ValueF(RecordLit( + ls.iter() + .filter_map(|l| { + kvs.get(l).map(|x| (l.clone(), x.clone())) + }) + .collect(), + )), + _ => { + drop(v_borrow); + Ret::Expr(expr) + } + } + } + ExprF::Field(ref v, ref l) => { + let v_borrow = v.as_whnf(); + match &*v_borrow { + RecordLit(kvs) => match kvs.get(l) { + Some(r) => Ret::Value(r.clone()), + None => { + drop(v_borrow); + Ret::Expr(expr) + } + }, + UnionType(kts) => { + Ret::ValueF(UnionConstructor(l.clone(), kts.clone())) + } + _ => { + drop(v_borrow); + Ret::Expr(expr) + } + } + } + ExprF::ProjectionByExpr(_, _) => { + unimplemented!("selection by expression") + } + + ExprF::Merge(ref handlers, ref variant, _) => { + let handlers_borrow = handlers.as_whnf(); + let variant_borrow = variant.as_whnf(); + match (&*handlers_borrow, &*variant_borrow) { + (RecordLit(kvs), UnionConstructor(l, _)) => match kvs.get(l) { + Some(h) => Ret::Value(h.clone()), + None => { + drop(handlers_borrow); + drop(variant_borrow); + Ret::Expr(expr) + } + }, + (RecordLit(kvs), UnionLit(l, v, _)) => match kvs.get(l) { + Some(h) => Ret::Value(h.app(v.clone())), + None => { + drop(handlers_borrow); + drop(variant_borrow); + Ret::Expr(expr) + } + }, + _ => { + drop(handlers_borrow); + drop(variant_borrow); + Ret::Expr(expr) + } + } + } + ExprF::ToMap(_, _) => unimplemented!("toMap"), + }; + + match ret { + Ret::ValueF(v) => v, + Ret::Value(v) => v.to_whnf_check_type(ty), + Ret::ValueRef(v) => v.to_whnf_check_type(ty), + Ret::Expr(expr) => ValueF::PartialExpr(expr), + } +} + +/// Normalize a ValueF into WHNF +pub(crate) fn normalize_whnf(v: ValueF, ty: &Value) -> ValueF { + match v { + ValueF::AppliedBuiltin(b, args) => apply_builtin(b, args, ty), + ValueF::PartialExpr(e) => normalize_one_layer(e, ty), + ValueF::TextLit(elts) => { + ValueF::TextLit(squash_textlit(elts.into_iter())) + } + // All other cases are already in WHNF + v => v, + } +} -- cgit v1.2.3