Refactoring

src/rukka_lang/mod.rs

@@ -71,14 +71,12 @@ impl EvaluatorState {
   fn eval(&mut self, expr: Sexp) -> Result<Sexp, String> {
     use self::Sexp::*;
     Ok(match expr {
-      SymbolAtom(ref sym) => {
-        match self.get_var(sym) {
+      SymbolAtom(ref sym) => match self.get_var(sym) {
         Some(ref sexp) => {
           let q: &Sexp = sexp; //WTF? if I delete this line, the copy doesn't work??
           q.clone() //TODO make this not involve a clone
         },
         None => return Err(format!("Variable {} not bound", sym)),
-        }
       },
       expr @ StringAtom(_) => expr,
       expr @ NumberAtom(_) => expr,
@@ -86,7 +84,23 @@ impl EvaluatorState {
       False => False,
       Cons(box operator, box operands) => {
         match operator {
-          SymbolAtom(ref sym) => match &sym[..] {
+          SymbolAtom(sym) => match &sym[..] {
+            "quote" | "eq?" | "cons" | "car" | "cdr" | "atom?" |
+              "define" | "lambda" | "if" | "cond" => self.eval_special_form(&sym[..], operands)?,
+            _ => {
+              let evaled = self.eval(SymbolAtom(sym))?;
+              self.apply(evaled, operands)?
+            }
+          },
+          _ => unimplemented!()
+        }
+      },
+      Nil => Nil,
+    })
+  }
+  fn eval_special_form(&mut self, form: &str, operands: Sexp) -> Result<Sexp, String> {
+    use self::Sexp::*;
+    Ok(match form {
       "quote" => operands,
       "eq?" => match operands {
         Cons(box lhs, box Cons(box rhs, _)) => {
@@ -143,13 +157,12 @@ impl EvaluatorState {
         _ => return Err(format!("Bad if expression"))
       },
       _ => unimplemented!(),
-          },
-          other => {println!("OTHER? {:?}", other); unimplemented!() }
-        }
-      },
-      Nil => Nil,
     })
   }
+
+  fn apply(&mut self, function: Sexp, operands: Sexp) -> Result<Sexp, String> {
+    Err(format!("Not implemented"))
+  }
 }
 
 fn read(input: &str) -> Result<Vec<Sexp>, String> {