Type checking beginnings

src/language.rs

@@ -77,6 +77,7 @@ impl TraceArtifact {
     let color = match stage {
       "parse_trace" => "red",
       "tokens" => "green",
+      "type_check" => "magenta",
       _ => "blue",
     };
     TraceArtifact { stage_name: stage.to_string(), debug_output: debug, text_color: color}

src/schala_lang/eval.rs

@@ -3,6 +3,11 @@ use schala_lang::parsing::AST;
 pub struct ReplState {
 }
 
+pub enum TypeCheck {
+  OK,
+  Error(String)
+}
+
 impl ReplState {
   pub fn new() -> ReplState {
     ReplState { }
@@ -11,5 +16,9 @@ impl ReplState {
   pub fn evaluate(&mut self, ast: AST) -> String {
     format!("Evaluated AST: {:?}", ast)
   }
+
+  pub fn type_check(&mut self, ast: &AST) -> TypeCheck {
+    TypeCheck::Error("type lol".to_string())
+  }
 }
 

src/schala_lang/mod.rs

@@ -4,6 +4,8 @@ use language::{ProgrammingLanguageInterface, EvalOptions, TraceArtifact, ReplOut
 mod parsing;
 mod eval;
 
+use self::eval::TypeCheck;
+
 pub struct Schala {
   state: eval::ReplState
 }
@@ -53,6 +55,15 @@ impl ProgrammingLanguageInterface for Schala {
       }
     };
 
+    match self.state.type_check(&ast) {
+      TypeCheck::OK => (),
+      TypeCheck::Error(s) => {
+        output.add_artifact(TraceArtifact::new("type_check", s));
+        output.add_output(format!("Type error"));
+        return output;
+      }
+    }
+
     let evaluation_output = self.state.evaluate(ast);
     output.add_output(evaluation_output);
     return output;