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Diffstat (limited to 'dhall/src/builtins.rs')
| -rw-r--r-- | dhall/src/builtins.rs | 608 |
1 files changed, 608 insertions, 0 deletions
diff --git a/dhall/src/builtins.rs b/dhall/src/builtins.rs new file mode 100644 index 0000000..67929a0 --- /dev/null +++ b/dhall/src/builtins.rs @@ -0,0 +1,608 @@ +use std::collections::{BTreeMap, HashMap}; +use std::convert::TryInto; + +use crate::operations::{BinOp, OpKind}; +use crate::semantics::{ + skip_resolve_expr, typecheck, Hir, HirKind, Nir, NirKind, NzEnv, VarEnv, +}; +use crate::syntax::Const::Type; +use crate::syntax::{ + Const, Expr, ExprKind, InterpolatedText, InterpolatedTextContents, Label, + NaiveDouble, NumKind, Span, UnspannedExpr, V, +}; + +/// Built-ins +#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)] +pub enum Builtin { + Bool, + Natural, + Integer, + Double, + Text, + List, + Optional, + OptionalNone, + NaturalBuild, + NaturalFold, + NaturalIsZero, + NaturalEven, + NaturalOdd, + NaturalToInteger, + NaturalShow, + NaturalSubtract, + IntegerToDouble, + IntegerShow, + IntegerNegate, + IntegerClamp, + DoubleShow, + ListBuild, + ListFold, + ListLength, + ListHead, + ListLast, + ListIndexed, + ListReverse, + OptionalFold, + OptionalBuild, + TextShow, +} + +impl Builtin { + pub fn parse(s: &str) -> Option<Self> { + use Builtin::*; + match s { + "Bool" => Some(Bool), + "Natural" => Some(Natural), + "Integer" => Some(Integer), + "Double" => Some(Double), + "Text" => Some(Text), + "List" => Some(List), + "Optional" => Some(Optional), + "None" => Some(OptionalNone), + "Natural/build" => Some(NaturalBuild), + "Natural/fold" => Some(NaturalFold), + "Natural/isZero" => Some(NaturalIsZero), + "Natural/even" => Some(NaturalEven), + "Natural/odd" => Some(NaturalOdd), + "Natural/toInteger" => Some(NaturalToInteger), + "Natural/show" => Some(NaturalShow), + "Natural/subtract" => Some(NaturalSubtract), + "Integer/toDouble" => Some(IntegerToDouble), + "Integer/show" => Some(IntegerShow), + "Integer/negate" => Some(IntegerNegate), + "Integer/clamp" => Some(IntegerClamp), + "Double/show" => Some(DoubleShow), + "List/build" => Some(ListBuild), + "List/fold" => Some(ListFold), + "List/length" => Some(ListLength), + "List/head" => Some(ListHead), + "List/last" => Some(ListLast), + "List/indexed" => Some(ListIndexed), + "List/reverse" => Some(ListReverse), + "Optional/fold" => Some(OptionalFold), + "Optional/build" => Some(OptionalBuild), + "Text/show" => Some(TextShow), + _ => None, + } + } +} + +/// A partially applied builtin. +/// Invariant: the evaluation of the given args must not be able to progress further +#[derive(Debug, Clone)] +pub struct BuiltinClosure { + env: NzEnv, + b: Builtin, + /// Arguments applied to the closure so far. + args: Vec<Nir>, +} + +impl BuiltinClosure { + pub fn new(b: Builtin, env: NzEnv) -> NirKind { + apply_builtin(b, Vec::new(), env) + } + pub fn apply(&self, a: Nir) -> NirKind { + use std::iter::once; + let args = self.args.iter().cloned().chain(once(a)).collect(); + apply_builtin(self.b, args, self.env.clone()) + } + pub fn to_hirkind(&self, venv: VarEnv) -> HirKind { + HirKind::Expr(self.args.iter().fold( + ExprKind::Builtin(self.b), + |acc, v| { + ExprKind::Op(OpKind::App( + Hir::new(HirKind::Expr(acc), Span::Artificial), + v.to_hir(venv), + )) + }, + )) + } +} + +pub fn rc(x: UnspannedExpr) -> Expr { + Expr::new(x, Span::Artificial) +} + +// Ad-hoc macro to help construct the types of builtins +macro_rules! make_type { + (Type) => { rc(ExprKind::Const(Const::Type)) }; + (Bool) => { rc(ExprKind::Builtin(Builtin::Bool)) }; + (Natural) => { rc(ExprKind::Builtin(Builtin::Natural)) }; + (Integer) => { rc(ExprKind::Builtin(Builtin::Integer)) }; + (Double) => { rc(ExprKind::Builtin(Builtin::Double)) }; + (Text) => { rc(ExprKind::Builtin(Builtin::Text)) }; + ($var:ident) => { + rc(ExprKind::Var(V(stringify!($var).into(), 0))) + }; + (Optional $ty:ident) => { + rc(ExprKind::Op(OpKind::App( + rc(ExprKind::Builtin(Builtin::Optional)), + make_type!($ty) + ))) + }; + (List $($rest:tt)*) => { + rc(ExprKind::Op(OpKind::App( + rc(ExprKind::Builtin(Builtin::List)), + make_type!($($rest)*) + ))) + }; + ({ $($label:ident : $ty:ident),* }) => {{ + let mut kts = BTreeMap::new(); + $( + kts.insert( + Label::from(stringify!($label)), + make_type!($ty), + ); + )* + rc(ExprKind::RecordType(kts)) + }}; + ($ty:ident -> $($rest:tt)*) => { + rc(ExprKind::Pi( + "_".into(), + make_type!($ty), + make_type!($($rest)*) + )) + }; + (($($arg:tt)*) -> $($rest:tt)*) => { + rc(ExprKind::Pi( + "_".into(), + make_type!($($arg)*), + make_type!($($rest)*) + )) + }; + (forall ($var:ident : $($ty:tt)*) -> $($rest:tt)*) => { + rc(ExprKind::Pi( + stringify!($var).into(), + make_type!($($ty)*), + make_type!($($rest)*) + )) + }; +} + +pub fn type_of_builtin(b: Builtin) -> Hir { + use Builtin::*; + let expr = match b { + Bool | Natural | Integer | Double | Text => make_type!(Type), + List | Optional => make_type!( + Type -> Type + ), + + NaturalFold => make_type!( + Natural -> + forall (natural: Type) -> + forall (succ: natural -> natural) -> + forall (zero: natural) -> + natural + ), + NaturalBuild => make_type!( + (forall (natural: Type) -> + forall (succ: natural -> natural) -> + forall (zero: natural) -> + natural) -> + Natural + ), + NaturalIsZero | NaturalEven | NaturalOdd => make_type!( + Natural -> Bool + ), + NaturalToInteger => make_type!(Natural -> Integer), + NaturalShow => make_type!(Natural -> Text), + NaturalSubtract => make_type!(Natural -> Natural -> Natural), + + IntegerToDouble => make_type!(Integer -> Double), + IntegerShow => make_type!(Integer -> Text), + IntegerNegate => make_type!(Integer -> Integer), + IntegerClamp => make_type!(Integer -> Natural), + + DoubleShow => make_type!(Double -> Text), + TextShow => make_type!(Text -> Text), + + ListBuild => make_type!( + forall (a: Type) -> + (forall (list: Type) -> + forall (cons: a -> list -> list) -> + forall (nil: list) -> + list) -> + List a + ), + ListFold => make_type!( + forall (a: Type) -> + (List a) -> + forall (list: Type) -> + forall (cons: a -> list -> list) -> + forall (nil: list) -> + list + ), + ListLength => make_type!(forall (a: Type) -> (List a) -> Natural), + ListHead | ListLast => { + make_type!(forall (a: Type) -> (List a) -> Optional a) + } + ListIndexed => make_type!( + forall (a: Type) -> + (List a) -> + List { index: Natural, value: a } + ), + ListReverse => make_type!( + forall (a: Type) -> (List a) -> List a + ), + + OptionalBuild => make_type!( + forall (a: Type) -> + (forall (optional: Type) -> + forall (just: a -> optional) -> + forall (nothing: optional) -> + optional) -> + Optional a + ), + OptionalFold => make_type!( + forall (a: Type) -> + (Optional a) -> + forall (optional: Type) -> + forall (just: a -> optional) -> + forall (nothing: optional) -> + optional + ), + OptionalNone => make_type!( + forall (A: Type) -> Optional A + ), + }; + skip_resolve_expr(&expr).unwrap() +} + +// Ad-hoc macro to help construct closures +macro_rules! make_closure { + (var($var:ident)) => {{ + rc(ExprKind::Var(V( + Label::from(stringify!($var)).into(), + 0 + ))) + }}; + (λ($var:tt : $($ty:tt)*) -> $($body:tt)*) => {{ + let var = Label::from(stringify!($var)); + let ty = make_closure!($($ty)*); + let body = make_closure!($($body)*); + rc(ExprKind::Lam(var, ty, body)) + }}; + (Type) => { + rc(ExprKind::Const(Type)) + }; + (Natural) => { + rc(ExprKind::Builtin(Builtin::Natural)) + }; + (List $($ty:tt)*) => {{ + let ty = make_closure!($($ty)*); + rc(ExprKind::Op(OpKind::App( + rc(ExprKind::Builtin(Builtin::List)), + ty + ))) + }}; + (Some($($v:tt)*)) => { + rc(ExprKind::SomeLit( + make_closure!($($v)*) + )) + }; + (1 + $($v:tt)*) => { + rc(ExprKind::Op(OpKind::BinOp( + BinOp::NaturalPlus, + make_closure!($($v)*), + rc(ExprKind::Num(NumKind::Natural(1))) + ))) + }; + ([ $($head:tt)* ] # $($tail:tt)*) => {{ + let head = make_closure!($($head)*); + let tail = make_closure!($($tail)*); + rc(ExprKind::Op(OpKind::BinOp( + BinOp::ListAppend, + rc(ExprKind::NEListLit(vec![head])), + tail, + ))) + }}; +} + +#[allow(clippy::cognitive_complexity)] +fn apply_builtin(b: Builtin, args: Vec<Nir>, env: NzEnv) -> NirKind { + use NirKind::*; + use NumKind::{Bool, Double, Integer, Natural}; + + // Small helper enum + enum Ret { + NirKind(NirKind), + Nir(Nir), + DoneAsIs, + } + let make_closure = |e| { + typecheck(&skip_resolve_expr(&e).unwrap()) + .unwrap() + .eval(env.clone()) + }; + + let ret = match (b, args.as_slice()) { + (Builtin::Bool, []) + | (Builtin::Natural, []) + | (Builtin::Integer, []) + | (Builtin::Double, []) + | (Builtin::Text, []) => Ret::NirKind(BuiltinType(b)), + (Builtin::Optional, [t]) => Ret::NirKind(OptionalType(t.clone())), + (Builtin::List, [t]) => Ret::NirKind(ListType(t.clone())), + + (Builtin::OptionalNone, [t]) => { + Ret::NirKind(EmptyOptionalLit(t.clone())) + } + (Builtin::NaturalIsZero, [n]) => match &*n.kind() { + Num(Natural(n)) => Ret::NirKind(Num(Bool(*n == 0))), + _ => Ret::DoneAsIs, + }, + (Builtin::NaturalEven, [n]) => match &*n.kind() { + Num(Natural(n)) => Ret::NirKind(Num(Bool(*n % 2 == 0))), + _ => Ret::DoneAsIs, + }, + (Builtin::NaturalOdd, [n]) => match &*n.kind() { + Num(Natural(n)) => Ret::NirKind(Num(Bool(*n % 2 != 0))), + _ => Ret::DoneAsIs, + }, + (Builtin::NaturalToInteger, [n]) => match &*n.kind() { + Num(Natural(n)) => Ret::NirKind(Num(Integer(*n as isize))), + _ => Ret::DoneAsIs, + }, + (Builtin::NaturalShow, [n]) => match &*n.kind() { + Num(Natural(n)) => Ret::Nir(Nir::from_text(n)), + _ => Ret::DoneAsIs, + }, + (Builtin::NaturalSubtract, [a, b]) => match (&*a.kind(), &*b.kind()) { + (Num(Natural(a)), Num(Natural(b))) => { + Ret::NirKind(Num(Natural(if b > a { b - a } else { 0 }))) + } + (Num(Natural(0)), _) => Ret::Nir(b.clone()), + (_, Num(Natural(0))) => Ret::NirKind(Num(Natural(0))), + _ if a == b => Ret::NirKind(Num(Natural(0))), + _ => Ret::DoneAsIs, + }, + (Builtin::IntegerShow, [n]) => match &*n.kind() { + Num(Integer(n)) => { + let s = if *n < 0 { + n.to_string() + } else { + format!("+{}", n) + }; + Ret::Nir(Nir::from_text(s)) + } + _ => Ret::DoneAsIs, + }, + (Builtin::IntegerToDouble, [n]) => match &*n.kind() { + Num(Integer(n)) => { + Ret::NirKind(Num(Double(NaiveDouble::from(*n as f64)))) + } + _ => Ret::DoneAsIs, + }, + (Builtin::IntegerNegate, [n]) => match &*n.kind() { + Num(Integer(n)) => Ret::NirKind(Num(Integer(-n))), + _ => Ret::DoneAsIs, + }, + (Builtin::IntegerClamp, [n]) => match &*n.kind() { + Num(Integer(n)) => { + Ret::NirKind(Num(Natural((*n).try_into().unwrap_or(0)))) + } + _ => Ret::DoneAsIs, + }, + (Builtin::DoubleShow, [n]) => match &*n.kind() { + Num(Double(n)) => Ret::Nir(Nir::from_text(n)), + _ => Ret::DoneAsIs, + }, + (Builtin::TextShow, [v]) => match &*v.kind() { + TextLit(tlit) => { + if let Some(s) = tlit.as_text() { + // Printing InterpolatedText takes care of all the escaping + let txt: InterpolatedText<Expr> = + std::iter::once(InterpolatedTextContents::Text(s)) + .collect(); + Ret::Nir(Nir::from_text(txt)) + } else { + Ret::DoneAsIs + } + } + _ => Ret::DoneAsIs, + }, + (Builtin::ListLength, [_, l]) => match &*l.kind() { + EmptyListLit(_) => Ret::NirKind(Num(Natural(0))), + NEListLit(xs) => Ret::NirKind(Num(Natural(xs.len()))), + _ => Ret::DoneAsIs, + }, + (Builtin::ListHead, [_, l]) => match &*l.kind() { + EmptyListLit(n) => Ret::NirKind(EmptyOptionalLit(n.clone())), + NEListLit(xs) => { + Ret::NirKind(NEOptionalLit(xs.iter().next().unwrap().clone())) + } + _ => Ret::DoneAsIs, + }, + (Builtin::ListLast, [_, l]) => match &*l.kind() { + EmptyListLit(n) => Ret::NirKind(EmptyOptionalLit(n.clone())), + NEListLit(xs) => Ret::NirKind(NEOptionalLit( + xs.iter().rev().next().unwrap().clone(), + )), + _ => Ret::DoneAsIs, + }, + (Builtin::ListReverse, [_, l]) => match &*l.kind() { + EmptyListLit(n) => Ret::NirKind(EmptyListLit(n.clone())), + NEListLit(xs) => { + Ret::NirKind(NEListLit(xs.iter().rev().cloned().collect())) + } + _ => Ret::DoneAsIs, + }, + (Builtin::ListIndexed, [t, l]) => { + match l.kind() { + EmptyListLit(_) | NEListLit(_) => { + // Construct the returned record type: { index: Natural, value: t } + let mut kts = HashMap::new(); + kts.insert( + "index".into(), + Nir::from_builtin(Builtin::Natural), + ); + kts.insert("value".into(), t.clone()); + let t = Nir::from_kind(RecordType(kts)); + + // Construct the new list, with added indices + let list = match l.kind() { + EmptyListLit(_) => EmptyListLit(t), + NEListLit(xs) => NEListLit( + xs.iter() + .enumerate() + .map(|(i, e)| { + let mut kvs = HashMap::new(); + kvs.insert( + "index".into(), + Nir::from_kind(Num(Natural(i))), + ); + kvs.insert("value".into(), e.clone()); + Nir::from_kind(RecordLit(kvs)) + }) + .collect(), + ), + _ => unreachable!(), + }; + Ret::NirKind(list) + } + _ => Ret::DoneAsIs, + } + } + (Builtin::ListBuild, [t, f]) => { + let list_t = Nir::from_builtin(Builtin::List).app(t.clone()); + Ret::Nir( + f.app(list_t) + .app( + make_closure(make_closure!( + λ(T : Type) -> + λ(a : var(T)) -> + λ(as : List var(T)) -> + [ var(a) ] # var(as) + )) + .app(t.clone()), + ) + .app(EmptyListLit(t.clone()).into_nir()), + ) + } + (Builtin::ListFold, [_, l, _, cons, nil]) => match &*l.kind() { + EmptyListLit(_) => Ret::Nir(nil.clone()), + NEListLit(xs) => { + let mut v = nil.clone(); + for x in xs.iter().cloned().rev() { + v = cons.app(x).app(v); + } + Ret::Nir(v) + } + _ => Ret::DoneAsIs, + }, + (Builtin::OptionalBuild, [t, f]) => { + let optional_t = + Nir::from_builtin(Builtin::Optional).app(t.clone()); + Ret::Nir( + f.app(optional_t) + .app( + make_closure(make_closure!( + λ(T : Type) -> + λ(a : var(T)) -> + Some(var(a)) + )) + .app(t.clone()), + ) + .app(EmptyOptionalLit(t.clone()).into_nir()), + ) + } + (Builtin::OptionalFold, [_, v, _, just, nothing]) => match &*v.kind() { + EmptyOptionalLit(_) => Ret::Nir(nothing.clone()), + NEOptionalLit(x) => Ret::Nir(just.app(x.clone())), + _ => Ret::DoneAsIs, + }, + (Builtin::NaturalBuild, [f]) => Ret::Nir( + f.app(Nir::from_builtin(Builtin::Natural)) + .app(make_closure(make_closure!( + λ(x : Natural) -> + 1 + var(x) + ))) + .app(Num(Natural(0)).into_nir()), + ), + + (Builtin::NaturalFold, [n, t, succ, zero]) => match &*n.kind() { + Num(Natural(0)) => Ret::Nir(zero.clone()), + Num(Natural(n)) => { + let fold = Nir::from_builtin(Builtin::NaturalFold) + .app(Num(Natural(n - 1)).into_nir()) + .app(t.clone()) + .app(succ.clone()) + .app(zero.clone()); + Ret::Nir(succ.app(fold)) + } + _ => Ret::DoneAsIs, + }, + _ => Ret::DoneAsIs, + }; + match ret { + Ret::NirKind(v) => v, + Ret::Nir(v) => v.kind().clone(), + Ret::DoneAsIs => AppliedBuiltin(BuiltinClosure { b, args, env }), + } +} + +impl std::cmp::PartialEq for BuiltinClosure { + fn eq(&self, other: &Self) -> bool { + self.b == other.b && self.args == other.args + } +} +impl std::cmp::Eq for BuiltinClosure {} + +impl std::fmt::Display for Builtin { + fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result { + use Builtin::*; + f.write_str(match *self { + Bool => "Bool", + Natural => "Natural", + Integer => "Integer", + Double => "Double", + Text => "Text", + List => "List", + Optional => "Optional", + OptionalNone => "None", + NaturalBuild => "Natural/build", + NaturalFold => "Natural/fold", + NaturalIsZero => "Natural/isZero", + NaturalEven => "Natural/even", + NaturalOdd => "Natural/odd", + NaturalToInteger => "Natural/toInteger", + NaturalShow => "Natural/show", + NaturalSubtract => "Natural/subtract", + IntegerToDouble => "Integer/toDouble", + IntegerNegate => "Integer/negate", + IntegerClamp => "Integer/clamp", + IntegerShow => "Integer/show", + DoubleShow => "Double/show", + ListBuild => "List/build", + ListFold => "List/fold", + ListLength => "List/length", + ListHead => "List/head", + ListLast => "List/last", + ListIndexed => "List/indexed", + ListReverse => "List/reverse", + OptionalFold => "Optional/fold", + OptionalBuild => "Optional/build", + TextShow => "Text/show", + }) + } +} |