add first steps toward generic type inference

src/frontend.rs

@@ -133,7 +133,11 @@ impl Context {
         match &expr.kind {
             typed_ir::ExprKind::Literal(lit) => Ok(lit.clone()),
             typed_ir::ExprKind::Path(_) => todo!("evaluate path"),
-            typed_ir::ExprKind::Call { called, args } => todo!("evaluate call"),
+            typed_ir::ExprKind::Call {
+                called,
+                args,
+                genargs,
+            } => todo!("evaluate call"),
         }
     }
 
@@ -174,6 +178,7 @@ impl Context {
                     kind: typed_ir::ExprKind::Call {
                         called: self.callables.builtins.bitnot,
                         args: vec![a],
+                        genargs: vec![],
                     },
                     typ: self.types.primitives.infer,
                 }
@@ -185,6 +190,7 @@ impl Context {
                     kind: typed_ir::ExprKind::Call {
                         called: self.callables.builtins.xor,
                         args: vec![a, b],
+                        genargs: vec![],
                     },
                     typ: self.types.primitives.infer,
                 }
@@ -203,11 +209,17 @@ impl Context {
                         expected: called_callable.argcount(),
                     }));
                 }
+                let genargs_resolved = called_callable
+                    .genargs
+                    .iter()
+                    .map(|genarg| genarg.1)
+                    .collect();
                 typed_ir::Expr {
                     id,
                     kind: typed_ir::ExprKind::Call {
                         called,
                         args: args_resolved,
+                        genargs: genargs_resolved,
                     },
                     typ: self.types.primitives.infer,
                 }
@@ -270,6 +282,44 @@ impl Context {
         )))
     }
 
+    pub fn infer_expr_types(&self, expr: &typed_ir::Expr) -> typed_ir::Expr {
+        if self.types.is_fully_typed(expr.typ) {
+            // there is nothing more to infer
+            return expr.clone();
+        }
+        match &expr.kind {
+            typed_ir::ExprKind::Literal(_) => todo!(),
+            typed_ir::ExprKind::Path(_) => todo!(),
+            typed_ir::ExprKind::Call {
+                called,
+                args,
+                genargs,
+            } => {
+                let callee_def = self.callables.get(*called);
+                if self.types.is_fully_typed(callee_def.ret_type) {
+                    expr.clone().with_type(callee_def.ret_type)
+                } else {
+                    let args_typed: Vec<_> =
+                        args.iter().map(|ex| self.infer_expr_types(ex)).collect();
+                    let param_types: Vec<_> = callee_def.args.iter().map(|param| param.1).collect();
+                    let mut genargs = callee_def.genargs.clone();
+                    let inferred_args: Vec<_> = param_types
+                        .iter()
+                        .zip(args_typed)
+                        .map(|(param, arg)| {})
+                        .collect();
+                    expr.clone().with_type(callee_def.ret_type)
+                }
+            }
+        }
+    }
+
+    pub fn infer_types(&self, mut block: typed_ir::Block) -> typed_ir::Block {
+        let new_root = self.infer_expr_types(&block.expr);
+        block.expr = new_root;
+        block
+    }
+
     pub fn pretty_typed_block(
         &self,
         w: &mut dyn std::fmt::Write,
@@ -292,7 +342,11 @@ impl Context {
         let expr_pretty = match &expr.kind {
             typed_ir::ExprKind::Literal(_) => todo!(),
             typed_ir::ExprKind::Path(path) => format!("sig_{}", path.0),
-            typed_ir::ExprKind::Call { called, args } => {
+            typed_ir::ExprKind::Call {
+                called,
+                args,
+                genargs,
+            } => {
                 let args = args
                     .iter()
                     .map(|arg| {
@@ -301,7 +355,20 @@ impl Context {
                     })
                     .collect::<Result<Vec<_>, std::fmt::Error>>()?;
                 let callable = self.callables.get(*called);
-                format!("{}({})", callable.name(), args.join(", "))
+                let genargs = genargs
+                    .iter()
+                    .map(|param| {
+                        let mut type_str = String::new();
+                        self.types.pretty_type(&mut type_str, *param)?;
+                        Ok(type_str)
+                    })
+                    .collect::<Result<Vec<_>, std::fmt::Error>>()?;
+                format!(
+                    "{}<{}>({})",
+                    callable.name(),
+                    genargs.join(", "),
+                    args.join(", ")
+                )
             }
         };
         let mut type_pretty = String::new();

src/frontend/callable.rs

@@ -1,4 +1,4 @@
-use super::types::{GenericArg, Type, TypingContext};
+use super::types::{Type, TypingContext};
 
 #[derive(Debug, Copy, Clone, PartialOrd, PartialEq, Eq, Ord)]
 pub struct CallableId(pub usize);
@@ -6,7 +6,8 @@ pub struct CallableId(pub usize);
 pub struct Callable {
     pub name: String,
     pub args: Vec<(Option<String>, Type)>,
-    pub ret_type: Option<Type>,
+    pub genargs: Vec<(Option<String>, Type)>,
+    pub ret_type: Type,
 }
 
 impl<'ty> Callable {
@@ -38,22 +39,29 @@ impl CallableContext {
             reduce_or: CallableId(2),
         };
         let logic1 = typectx.make_logic_size(1);
+        let logic_tvar0 = typectx.make_typevar(0, 0);
         Self {
             callables: vec![
                 Callable {
                     name: "builtin::xor".to_string(),
-                    args: vec![],
+                    args: vec![
-                    ret_type: Some(typectx.primitives.logic),
+                        (Some("a".to_string()), logic_tvar0),
+                        (Some("b".to_string()), logic_tvar0),
+                    ],
+                    genargs: vec![(Some("T".to_string()), typectx.primitives.logic)],
+                    ret_type: logic_tvar0,
                 },
                 Callable {
                     name: "builtin::bitnot".to_string(),
-                    args: vec![],
+                    args: vec![(Some("a".to_string()), logic_tvar0)],
-                    ret_type: Some(typectx.primitives.logic),
+                    genargs: vec![(Some("T".to_string()), typectx.primitives.logic)],
+                    ret_type: logic_tvar0,
                 },
                 Callable {
                     name: "builtin::reduce_or".to_string(),
                     args: vec![(Some("a".to_string()), typectx.primitives.logic)],
-                    ret_type: Some(logic1),
+                    genargs: vec![],
+                    ret_type: logic1,
                 },
             ],
             builtins,

src/frontend/typed_ir.rs

@@ -32,7 +32,11 @@ pub struct Expr {
 pub enum ExprKind {
     Literal(ElabData),
     Path(DefId),
-    Call { called: CallableId, args: Vec<Expr> },
+    Call {
+        called: CallableId,
+        args: Vec<Expr>,
+        genargs: Vec<Type>,
+    },
 }
 
 #[derive(Debug, Clone)]
@@ -47,3 +51,10 @@ pub struct Block {
     pub signals: Vec<Signal>,
     pub expr: Expr,
 }
+
+impl Expr {
+    pub fn with_type(mut self, typ: Type) -> Self {
+        self.typ = typ;
+        self
+    }
+}

src/frontend/types.rs

@@ -30,6 +30,9 @@ enum TypeKind {
     Callable(FnSig),
     /// A type that was not given and needs to be inferred
     Infer,
+    /// A reference to a type variable as DeBruijn index
+    /// (scope, param)
+    TypeVar(u32, u32),
 }
 
 #[derive(Debug, Clone)]
@@ -131,6 +134,12 @@ impl TypingContext {
             .unwrap()
     }
 
+    pub fn make_typevar(&mut self, dbi: u32, tvar: u32) -> Type {
+        self.add(TypeStruct {
+            kind: TypeKind::TypeVar(dbi, tvar),
+        })
+    }
+
     pub fn parameterize(&mut self, typ: Type, params: &[GenericArg]) -> Option<Type> {
         // TODO: return proper error type here
         match &self.get(typ).kind {
@@ -159,7 +168,29 @@ impl TypingContext {
             TypeKind::UInt(_) => todo!(),
             TypeKind::Callable(_sig) => todo!("callable generic params"),
             // need to know what the type is to parameterize it
-            TypeKind::Infer => None,
+            TypeKind::Infer | &TypeKind::TypeVar(_, _) => None,
+        }
+    }
+
+    /// return whether the type has no unfilled parameters
+    pub fn is_fully_typed(&self, typ: Type) -> bool {
+        match &self.get(typ).kind {
+            TypeKind::ElabType(_) => todo!(),
+            TypeKind::Logic(data) => {
+                if let ElabValue::Concrete(_) = data.value {
+                    true
+                } else {
+                    false
+                }
+            }
+            TypeKind::UInt(_) => todo!(),
+            TypeKind::Callable(_) => todo!(),
+            TypeKind::Infer => false,
+            TypeKind::TypeVar(dbi, _tvar) => {
+                // if the DeBruijn index is 0, there is no further information to gain
+                // from a surrounding scope
+                *dbi != 0
+            }
         }
     }
 
@@ -185,6 +216,7 @@ impl TypingContext {
             TypeKind::Infer => write!(w, "?"),
             TypeKind::UInt(_) => todo!("print uint"),
             TypeKind::Callable(_sig) => todo!("print callable"),
+            TypeKind::TypeVar(_, tvar) => write!(w, "T{}", tvar),
         }
     }
 }

src/main.rs

@@ -67,8 +67,14 @@ fn main() {
                     frontendcontext
                         .pretty_typed_block(&mut pretty_block, &block)
                         .unwrap();
-                }
                     println!("{}", &pretty_block);
+                    let typed_inferred = frontendcontext.infer_types(block);
+                    let mut pretty_block = String::new();
+                    frontendcontext
+                        .pretty_typed_block(&mut pretty_block, &typed_inferred)
+                        .unwrap();
+                    println!("{}", &pretty_block);
+                }
             }
             /*
             match lowered {