implement type inference for literals

src/frontend.rs

@@ -292,7 +292,7 @@ impl Context {
             return expr.clone();
         }
         match &expr.kind {
-            typed_ir::ExprKind::Literal(_) => todo!(),
+            typed_ir::ExprKind::Literal(lit) => expr.clone().with_type(lit.typ),
             // we can not see beyond this expression right now
             typed_ir::ExprKind::Path(_) => expr.clone(),
             typed_ir::ExprKind::Call {
@@ -372,7 +372,11 @@ impl Context {
         expr: &typed_ir::Expr,
     ) -> std::fmt::Result {
         let expr_pretty = match &expr.kind {
-            typed_ir::ExprKind::Literal(_) => todo!(),
+            typed_ir::ExprKind::Literal(lit) => {
+                let mut lit_str = String::new();
+                self.types.pretty_value(&mut lit_str, lit)?;
+                lit_str
+            }
             typed_ir::ExprKind::Path(path) => format!("sig_{}", path.0),
             typed_ir::ExprKind::Call {
                 called,

src/frontend/types.rs

@@ -43,7 +43,7 @@ pub struct FnSig {
 
 #[derive(Debug, Clone)]
 pub struct ElabData {
-    typ: Type,
+    pub typ: Type,
     value: ElabValue,
 }