Buildtins

src/exec/builtin_definitions.rs

@@ -0,0 +1,352 @@
+use std::rc::Rc;
+
+use crate::{
+    parse::Constant,
+    types::{PrimitiveType, TaggedType, Type, TypeTag},
+};
+
+use super::{
+    DeBrujinAst,
+    builtins::{Builtin, DeBrujinBuiltInAst},
+};
+
+pub struct AddOp;
+struct AddOpNat(usize);
+struct AddOpFloat(f64);
+
+impl Builtin for AddOp {
+    fn name(&self) -> String {
+        "add".to_string()
+    }
+
+    fn r#type(&self) -> TaggedType {
+        TaggedType::Tagged(
+            TypeTag::Num,
+            "a".to_string(),
+            Box::new(TaggedType::Concrete(Type::arrow(
+                "a",
+                Type::arrow("a", "a"),
+            ))),
+        )
+    }
+
+    fn apply(&self, rhs: DeBrujinBuiltInAst) -> Option<DeBrujinBuiltInAst> {
+        match rhs {
+            DeBrujinBuiltInAst::Constant(Constant::Nat(n)) => {
+                Some(DeBrujinBuiltInAst::Builtin(Rc::new(AddOpNat(n))))
+            }
+            DeBrujinBuiltInAst::Constant(Constant::Float(n)) => {
+                Some(DeBrujinBuiltInAst::Builtin(Rc::new(AddOpFloat(n))))
+            }
+            _ => None,
+        }
+    }
+}
+
+impl Builtin for AddOpNat {
+    fn name(&self) -> String {
+        format!("add{}", self.0)
+    }
+
+    fn to_ast(&self) -> DeBrujinAst {
+        DeBrujinAst::Application(
+            Box::new(DeBrujinAst::FreeVariable("add".to_string())),
+            Box::new(DeBrujinAst::Constant(Constant::Nat(self.0))),
+        )
+    }
+
+    fn r#type(&self) -> TaggedType {
+        Type::arrow(PrimitiveType::Nat, PrimitiveType::Nat).into()
+    }
+
+    fn apply(&self, rhs: DeBrujinBuiltInAst) -> Option<DeBrujinBuiltInAst> {
+        match rhs {
+            DeBrujinBuiltInAst::Constant(Constant::Nat(n)) => {
+                Some(DeBrujinBuiltInAst::Constant(Constant::Nat(n + self.0)))
+            }
+            _ => None,
+        }
+    }
+}
+
+impl Builtin for AddOpFloat {
+    fn name(&self) -> String {
+        format!("add{}", self.0)
+    }
+
+    fn to_ast(&self) -> DeBrujinAst {
+        DeBrujinAst::Application(
+            Box::new(DeBrujinAst::FreeVariable("add".to_string())),
+            Box::new(DeBrujinAst::Constant(Constant::Float(self.0))),
+        )
+    }
+
+    fn r#type(&self) -> TaggedType {
+        Type::arrow(PrimitiveType::Float, PrimitiveType::Float).into()
+    }
+
+    fn apply(&self, rhs: DeBrujinBuiltInAst) -> Option<DeBrujinBuiltInAst> {
+        match rhs {
+            DeBrujinBuiltInAst::Constant(Constant::Float(n)) => {
+                Some(DeBrujinBuiltInAst::Constant(Constant::Float(n + self.0)))
+            }
+            _ => None,
+        }
+    }
+}
+
+pub struct SubOp;
+struct SubOpNat(usize);
+struct SubOpFloat(f64);
+
+impl Builtin for SubOp {
+    fn name(&self) -> String {
+        "sub".to_string()
+    }
+
+    fn r#type(&self) -> TaggedType {
+        TaggedType::Tagged(
+            TypeTag::Num,
+            "a".to_string(),
+            Box::new(TaggedType::Concrete(Type::arrow(
+                "a",
+                Type::arrow("a", "a"),
+            ))),
+        )
+    }
+
+    fn apply(&self, rhs: DeBrujinBuiltInAst) -> Option<DeBrujinBuiltInAst> {
+        match rhs {
+            DeBrujinBuiltInAst::Constant(Constant::Nat(n)) => {
+                Some(DeBrujinBuiltInAst::Builtin(Rc::new(SubOpNat(n))))
+            }
+            DeBrujinBuiltInAst::Constant(Constant::Float(n)) => {
+                Some(DeBrujinBuiltInAst::Builtin(Rc::new(SubOpFloat(n))))
+            }
+            _ => None,
+        }
+    }
+}
+
+impl Builtin for SubOpNat {
+    fn name(&self) -> String {
+        format!("sub{}", self.0)
+    }
+
+    fn to_ast(&self) -> DeBrujinAst {
+        DeBrujinAst::Application(
+            Box::new(DeBrujinAst::FreeVariable("sub".to_string())),
+            Box::new(DeBrujinAst::Constant(Constant::Nat(self.0))),
+        )
+    }
+
+    fn r#type(&self) -> TaggedType {
+        Type::arrow(PrimitiveType::Nat, PrimitiveType::Nat).into()
+    }
+
+    fn apply(&self, rhs: DeBrujinBuiltInAst) -> Option<DeBrujinBuiltInAst> {
+        match rhs {
+            DeBrujinBuiltInAst::Constant(Constant::Nat(n)) => {
+                Some(DeBrujinBuiltInAst::Constant(Constant::Nat(self.0 - n)))
+            }
+            _ => None,
+        }
+    }
+}
+
+impl Builtin for SubOpFloat {
+    fn name(&self) -> String {
+        format!("sub{}", self.0)
+    }
+
+    fn to_ast(&self) -> DeBrujinAst {
+        DeBrujinAst::Application(
+            Box::new(DeBrujinAst::FreeVariable("sub".to_string())),
+            Box::new(DeBrujinAst::Constant(Constant::Float(self.0))),
+        )
+    }
+
+    fn r#type(&self) -> TaggedType {
+        Type::arrow(PrimitiveType::Float, PrimitiveType::Float).into()
+    }
+
+    fn apply(&self, rhs: DeBrujinBuiltInAst) -> Option<DeBrujinBuiltInAst> {
+        match rhs {
+            DeBrujinBuiltInAst::Constant(Constant::Float(n)) => {
+                Some(DeBrujinBuiltInAst::Constant(Constant::Float(self.0 - n)))
+            }
+            _ => None,
+        }
+    }
+}
+
+pub struct MulOp;
+struct MulOpNat(usize);
+struct MulOpFloat(f64);
+
+impl Builtin for MulOp {
+    fn name(&self) -> String {
+        "mul".to_string()
+    }
+
+    fn r#type(&self) -> TaggedType {
+        TaggedType::Tagged(
+            TypeTag::Num,
+            "a".to_string(),
+            Box::new(TaggedType::Concrete(Type::arrow(
+                "a",
+                Type::arrow("a", "a"),
+            ))),
+        )
+    }
+
+    fn apply(&self, rhs: DeBrujinBuiltInAst) -> Option<DeBrujinBuiltInAst> {
+        match rhs {
+            DeBrujinBuiltInAst::Constant(Constant::Nat(n)) => {
+                Some(DeBrujinBuiltInAst::Builtin(Rc::new(MulOpNat(n))))
+            }
+            DeBrujinBuiltInAst::Constant(Constant::Float(n)) => {
+                Some(DeBrujinBuiltInAst::Builtin(Rc::new(MulOpFloat(n))))
+            }
+            _ => None,
+        }
+    }
+}
+
+impl Builtin for MulOpNat {
+    fn name(&self) -> String {
+        format!("mul{}", self.0)
+    }
+
+    fn to_ast(&self) -> DeBrujinAst {
+        DeBrujinAst::Application(
+            Box::new(DeBrujinAst::FreeVariable("mul".to_string())),
+            Box::new(DeBrujinAst::Constant(Constant::Nat(self.0))),
+        )
+    }
+
+    fn r#type(&self) -> TaggedType {
+        Type::arrow(PrimitiveType::Nat, PrimitiveType::Nat).into()
+    }
+
+    fn apply(&self, rhs: DeBrujinBuiltInAst) -> Option<DeBrujinBuiltInAst> {
+        match rhs {
+            DeBrujinBuiltInAst::Constant(Constant::Nat(n)) => {
+                Some(DeBrujinBuiltInAst::Constant(Constant::Nat(n * self.0)))
+            }
+            _ => None,
+        }
+    }
+}
+
+impl Builtin for MulOpFloat {
+    fn name(&self) -> String {
+        format!("mul{}", self.0)
+    }
+
+    fn to_ast(&self) -> DeBrujinAst {
+        DeBrujinAst::Application(
+            Box::new(DeBrujinAst::FreeVariable("mul".to_string())),
+            Box::new(DeBrujinAst::Constant(Constant::Float(self.0))),
+        )
+    }
+
+    fn r#type(&self) -> TaggedType {
+        Type::arrow(PrimitiveType::Float, PrimitiveType::Float).into()
+    }
+
+    fn apply(&self, rhs: DeBrujinBuiltInAst) -> Option<DeBrujinBuiltInAst> {
+        match rhs {
+            DeBrujinBuiltInAst::Constant(Constant::Float(n)) => {
+                Some(DeBrujinBuiltInAst::Constant(Constant::Float(n * self.0)))
+            }
+            _ => None,
+        }
+    }
+}
+
+pub struct OpCond;
+struct OpCond1(bool);
+struct OpCond2(bool, DeBrujinBuiltInAst);
+
+impl Builtin for OpCond {
+    fn name(&self) -> String {
+        "if".to_string()
+    }
+
+    fn r#type(&self) -> TaggedType {
+        TaggedType::Tagged(
+            TypeTag::Any,
+            "a".to_string(),
+            Box::new(TaggedType::Concrete(Type::arrow(
+                PrimitiveType::Bool,
+                Type::arrow("a", Type::arrow("a", "a")),
+            ))),
+        )
+    }
+
+    fn apply(&self, rhs: DeBrujinBuiltInAst) -> Option<DeBrujinBuiltInAst> {
+        match rhs {
+            DeBrujinBuiltInAst::Constant(Constant::Bool(b)) => {
+                Some(DeBrujinBuiltInAst::Builtin(Rc::new(OpCond1(b))))
+            }
+            _ => None,
+        }
+    }
+}
+
+impl Builtin for OpCond1 {
+    fn name(&self) -> String {
+        format!("if{}1", self.0)
+    }
+
+    fn r#type(&self) -> TaggedType {
+        TaggedType::Tagged(
+            TypeTag::Any,
+            "a".to_string(),
+            Box::new(TaggedType::Concrete(Type::arrow(
+                "a",
+                Type::arrow("a", "a"),
+            ))),
+        )
+    }
+
+    fn to_ast(&self) -> DeBrujinAst {
+        DeBrujinAst::Application(
+            Box::new(DeBrujinAst::FreeVariable("if".to_string())),
+            Box::new(DeBrujinAst::Constant(Constant::Bool(self.0))),
+        )
+    }
+
+    fn apply(&self, rhs: DeBrujinBuiltInAst) -> Option<DeBrujinBuiltInAst> {
+        Some(DeBrujinBuiltInAst::Builtin(Rc::new(OpCond2(self.0, rhs))))
+    }
+}
+
+impl Builtin for OpCond2 {
+    fn name(&self) -> String {
+        format!("if{}2", self.0)
+    }
+
+    fn r#type(&self) -> TaggedType {
+        TaggedType::Tagged(
+            TypeTag::Any,
+            "a".to_string(),
+            Box::new(TaggedType::Concrete(Type::arrow("a", "a"))),
+        )
+    }
+
+    fn to_ast(&self) -> DeBrujinAst {
+        DeBrujinAst::Application(
+            Box::new(DeBrujinAst::Application(
+                Box::new(DeBrujinAst::FreeVariable("if".to_string())),
+                Box::new(DeBrujinAst::Constant(Constant::Bool(self.0))),
+            )),
+            Box::new(self.1.clone().into()),
+        )
+    }
+
+    fn apply(&self, rhs: DeBrujinBuiltInAst) -> Option<DeBrujinBuiltInAst> {
+        Some(if self.0 { self.1.clone() } else { rhs })
+    }
+}

src/exec/builtins.rs

@@ -0,0 +1,101 @@
+use std::{collections::HashMap, rc::Rc, usize};
+
+use crate::{
+    parse::Constant,
+    types::{Ident, PrimitiveType, TaggedType, Type, TypeTag},
+};
+
+use super::DeBrujinAst;
+
+#[derive(Clone)]
+pub enum DeBrujinBuiltInAst {
+    Abstraction(Ident, Type, Box<DeBrujinBuiltInAst>), // \:1.2
+    Application(Box<DeBrujinBuiltInAst>, Box<DeBrujinBuiltInAst>), // 0 1
+    FreeVariable(String),                              // x
+    BoundVariable(usize),                              // 1
+    Constant(Constant),                                // true | false | n
+    Builtin(Rc<dyn Builtin>),
+}
+
+impl DeBrujinAst {
+    pub fn resolve_builtins(
+        self,
+        builtins: &HashMap<String, Rc<dyn Builtin>>,
+    ) -> DeBrujinBuiltInAst {
+        match self {
+            DeBrujinAst::Abstraction(i, t, ast) => {
+                DeBrujinBuiltInAst::Abstraction(i, t, Box::new(ast.resolve_builtins(builtins)))
+            }
+            DeBrujinAst::Application(lhs, rhs) => DeBrujinBuiltInAst::Application(
+                Box::new(lhs.resolve_builtins(builtins)),
+                Box::new(rhs.resolve_builtins(builtins)),
+            ),
+            DeBrujinAst::FreeVariable(x) => {
+                if let Some(b) = builtins.get(&x) {
+                    DeBrujinBuiltInAst::Builtin(b.clone())
+                } else {
+                    DeBrujinBuiltInAst::FreeVariable(x)
+                }
+            }
+            DeBrujinAst::BoundVariable(b) => DeBrujinBuiltInAst::BoundVariable(b),
+            DeBrujinAst::Constant(c) => DeBrujinBuiltInAst::Constant(c),
+        }
+    }
+}
+
+pub trait Builtin {
+    fn name(&self) -> String;
+
+    fn to_ast(&self) -> DeBrujinAst {
+        DeBrujinAst::FreeVariable(self.name())
+    }
+
+    fn r#type(&self) -> TaggedType;
+
+    fn apply(&self, rhs: DeBrujinBuiltInAst) -> Option<DeBrujinBuiltInAst>;
+}
+
+impl DeBrujinAst {
+    pub fn reduce_builtins(self, builtins: &HashMap<String, Rc<dyn Builtin>>) -> DeBrujinAst {
+        self.resolve_builtins(builtins).reduce_builtins().into()
+    }
+}
+
+impl DeBrujinBuiltInAst {
+    fn reduce_builtins(self) -> DeBrujinBuiltInAst {
+        match self {
+            DeBrujinBuiltInAst::Abstraction(i, t, ast) => {
+                DeBrujinBuiltInAst::Abstraction(i, t, Box::new(ast.reduce_builtins()))
+            }
+            DeBrujinBuiltInAst::Application(lhs, rhs) => match *lhs {
+                DeBrujinBuiltInAst::Builtin(builtin) => builtin
+                    .apply(*rhs)
+                    .expect("the type checker should make sure we can apply")
+                    .reduce_builtins(),
+                lhs => DeBrujinBuiltInAst::Application(
+                    Box::new(lhs.reduce_builtins()),
+                    Box::new(rhs.reduce_builtins()),
+                )
+                .reduce_builtins(),
+            },
+            a => a,
+        }
+    }
+}
+
+impl Into<DeBrujinAst> for DeBrujinBuiltInAst {
+    fn into(self) -> DeBrujinAst {
+        match self {
+            DeBrujinBuiltInAst::Abstraction(i, t, ast) => {
+                DeBrujinAst::Abstraction(i, t, Box::new((*ast).into()))
+            }
+            DeBrujinBuiltInAst::Application(lhs, rhs) => {
+                DeBrujinAst::Application(Box::new((*lhs).into()), Box::new((*rhs).into()))
+            }
+            DeBrujinBuiltInAst::FreeVariable(x) => DeBrujinAst::FreeVariable(x),
+            DeBrujinBuiltInAst::BoundVariable(i) => DeBrujinAst::BoundVariable(i),
+            DeBrujinBuiltInAst::Constant(constant) => DeBrujinAst::Constant(constant),
+            DeBrujinBuiltInAst::Builtin(builtin) => DeBrujinAst::FreeVariable(builtin.name()),
+        }
+    }
+}

src/exec/mod.rs

@@ -1,6 +1,11 @@
+pub mod builtin_definitions;
+mod builtins;
 #[cfg(test)]
 mod test;
 
+pub use builtin_definitions as builtin;
+pub use builtins::Builtin;
+
 use std::{collections::HashMap, rc::Rc};
 
 use crate::{
@@ -41,7 +46,7 @@ impl Ast {
     }
 }
 
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Debug, Clone, PartialEq)]
 pub enum DeBrujinAst {
     Abstraction(Ident, Type, Box<DeBrujinAst>),      // \:1.2
     Application(Box<DeBrujinAst>, Box<DeBrujinAst>), // 0 1

src/exec/test.rs

@@ -1,9 +1,13 @@
+use std::{collections::HashMap, rc::Rc};
+
 use crate::{
     PrimitiveType, Type,
-    exec::DeBrujinAst as DBAst,
+    exec::{DeBrujinAst as DBAst, builtin_definitions::AddOp},
     parse::{Ast, Constant},
 };
 
+use super::builtins::Builtin;
+
 #[test]
 fn to_de_brujin_ast_simple() {
     let input = Ast::Abstraction(
@@ -71,3 +75,19 @@ fn to_and_from_de_brujin_is_id() {
     let output: Ast = dbast.into();
     assert_eq!(input, output);
 }
+
+#[test]
+fn reduce_add() {
+    let input: DBAst = Ast::Application(
+        Box::new(Ast::Application(
+            Box::new(Ast::Variable("add".to_string())),
+            Box::new(Ast::Constant(Constant::Nat(5))),
+        )),
+        Box::new(Ast::Constant(Constant::Nat(5))),
+    )
+    .into();
+    let mut builtins: HashMap<String, Rc<dyn Builtin>> = HashMap::new();
+    builtins.insert("add".to_string(), Rc::new(AddOp));
+    let output = input.reduce_builtins(&builtins);
+    assert_eq!(output, DBAst::Constant(Constant::Nat(10)));
+}

src/lib.rs

@@ -8,7 +8,9 @@ mod parse;
 mod types;
 mod vec_map;
 
+pub use exec::Builtin;
 pub use exec::DeBrujinAst;
+pub use exec::builtin;
 pub use inference::infer_type;
 pub use parse::{Ast, ParseError, is_ident, parse, parse_type, sexpr::parse_string};
 use types::{Ident, PrimitiveType, Type};

src/main.rs

@@ -5,7 +5,7 @@ use std::{
 };
 
 use stlc_type_inference::{
-    Ast, DeBrujinAst, infer_type, is_ident, parse, parse_string, parse_type,
+    Ast, Builtin, DeBrujinAst, builtin, infer_type, is_ident, parse, parse_string, parse_type,
 };
 
 macro_rules! repl_err {
@@ -18,7 +18,15 @@ macro_rules! repl_err {
 }
 
 fn main() {
+    let mut builtins: HashMap<String, Rc<dyn Builtin>> = HashMap::new();
+    builtins.insert("add".to_string(), Rc::new(builtin::AddOp));
+    builtins.insert("sub".to_string(), Rc::new(builtin::SubOp));
+    builtins.insert("mul".to_string(), Rc::new(builtin::MulOp));
+    builtins.insert("if".to_string(), Rc::new(builtin::OpCond));
     let mut gamma = HashMap::new();
+    for (k, v) in &builtins {
+        gamma.insert(k.clone(), v.r#type());
+    }
     print!("> ");
     stdout().flush().unwrap();
     for line in stdin().lines() {
@@ -50,8 +58,12 @@ fn main() {
                                 Err(e) => repl_err!("type could not be parsed {e:?}"),
                             };
 
+                            if !gamma.contains_key(&ident) {
                                 println!("Added {ident} with type {typ} to the context");
                                 gamma.insert(ident, typ.into());
+                            } else {
+                                println!("Cannot override existing ctx");
+                            }
                         }
                     }
                     c => println!("Unknown command {c}"),
@@ -75,6 +87,7 @@ fn main() {
                 Err(e) => repl_err!("Could not infer type {e:?}"),
             };
             let ast = ast.beta_reduce();
+            let ast = ast.reduce_builtins(&builtins);
             let ast: Ast = ast.into();
             println!("{ast} : {typ}")
         }

src/parse/mod.rs

@@ -29,13 +29,14 @@ pub enum ParseError {
     ExpectedOneOf(Vec<String>, String),
 }
 
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Debug, Clone, PartialEq)]
 pub enum Constant {
     Nat(usize),
+    Float(f64),
     Bool(bool),
 }
 
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Debug, Clone, PartialEq)]
 pub enum Ast {
     Abstraction(Ident, Type, Box<Ast>), // \0:1.2
     Application(Box<Ast>, Box<Ast>),    // 0 1
@@ -59,6 +60,7 @@ impl Display for Constant {
         match self {
             Constant::Nat(n) => write!(f, "{n}"),
             Constant::Bool(b) => write!(f, "{b}"),
+            Constant::Float(fl) => write!(f, "{fl}"),
         }
     }
 }
@@ -172,6 +174,8 @@ fn parse_intern(ast: Sexpr) -> Result<Ast, ParseError> {
 fn parse_symbol(s: String) -> Result<Ast, ParseError> {
     if let Ok(n) = s.parse::<usize>() {
         Ok(Ast::Constant(Constant::Nat(n)))
+    } else if let Ok(f) = s.parse::<f64>() {
+        Ok(Ast::Constant(Constant::Float(f)))
     } else if let Ok(b) = s.parse::<bool>() {
         Ok(Ast::Constant(Constant::Bool(b)))
     } else if is_ident(&s) {

src/types/mod.rs

@@ -6,11 +6,13 @@ pub type Ident = String;
 pub enum PrimitiveType {
     Nat,
     Bool,
+    Float,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum TypeTag {
     Num,
+    Any,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -129,6 +131,12 @@ impl From<PrimitiveType> for Type {
     }
 }
 
+impl From<&str> for Type {
+    fn from(value: &str) -> Self {
+        Self::Generic(value.to_string())
+    }
+}
+
 impl Type {
     pub fn arrow<T1: Into<Type>, T2: Into<Type>>(t1: T1, t2: T2) -> Self {
         Self::Arrow(Box::new(t1.into()), Box::new(t2.into()))
@@ -146,6 +154,7 @@ impl Type {
         match self {
             Type::Generic(_) => false,
             Type::Primitive(primitive_type) => match (primitive_type, tag) {
+                (_, TypeTag::Any) => true,
                 (PrimitiveType::Nat, TypeTag::Num) => true,
                 _ => false,
             },
@@ -156,6 +165,7 @@ impl Type {
     fn name_used(&self, ident: &str) -> bool {
         match self {
             Type::Generic(i) if *i == ident => true,
+            Type::Arrow(lhs, rhs) => lhs.name_used(ident) || rhs.name_used(ident),
             _ => false,
         }
     }
@@ -176,6 +186,7 @@ impl Display for TypeTag {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
             TypeTag::Num => write!(f, "Num"),
+            TypeTag::Any => write!(f, "Any"),
         }
     }
 }
@@ -206,6 +217,7 @@ impl Display for PrimitiveType {
         match self {
             PrimitiveType::Nat => write!(f, "Nat"),
             PrimitiveType::Bool => write!(f, "Bool"),
+            PrimitiveType::Float => write!(f, "Float"),
         }
     }
 }