AST-walking infrastructure

schala-lang/language/src/typechecking.rs

@@ -142,6 +142,24 @@ impl<'a> TypeContext<'a> {
   }
 
   pub fn typecheck(&mut self, ast: &AST) -> Result<String, String> {
-    Ok(format!("UNIT"))
+    for statement in ast.0.iter() {
+      self.typecheck_statement(statement.node()).map_err(|err| { err.msg })?
+    }
+    Ok("unknown type".to_string())
+  }
+
+  fn typecheck_statement(&mut self, statement: &Statement) -> InferResult<()> {
+    match statement {
+      Statement::ExpressionStatement(e) => self.typecheck_expr(e.node()),
+      Statement::Declaration(decl) => self.typecheck_decl(decl),
+    }
+  }
+
+  fn typecheck_decl(&mut self, decl: &Declaration) -> InferResult<()> {
+    Ok(())
+  }
+
+  fn typecheck_expr(&mut self, expr: &Expression) -> InferResult<()> {
+    Ok(())
   }
 }