distinguish function calls from sym evaluation

prepare function call handling: till now, i've
just eval'ed new tokens but i think that i have
to distinguish a function call from a symbol
evaluation.

tokenize.l

@@ -161,6 +161,18 @@ int token_is_num(struct token *t) {return t->type == NUM;}
 int token_is_sym(struct token *t) {return t->type == SYM;}
 int token_is_str(struct token *t) {return t->type == STR;}
 int token_is_bool(struct token *t) {return t->type == BOOL;}
+int token_is_internal(struct token *t) {
+  if (strcmp(t->v.str, "def") == 0) return 1;
+  else if (strcmp(t->v.str, "lm") == 0) return 1;
+  else if (strcmp(t->v.str, "if") == 0) return 1;
+  else if (strcmp(t->v.str, "inv") == 0) return 1;
+  else if (strcmp(t->v.str, "add") == 0) return 1;
+  else if (strcmp(t->v.str, "lt") == 0) return 1;
+  else if (strcmp(t->v.str, "nand") == 0) return 1;
+  else if (strcmp(t->v.str, "q") == 0) return 1;
+  else return 0;
+}
+
 
 /* upon parsing a list of tokens like:
  *    "(" -> "def" -> "(" -> "b" -> ")" -> "c" -> ")"
@@ -351,7 +363,7 @@ eval_inv(struct ast *a, struct env *e)
 }
 
 struct ast *
-eval_sym(struct ast *a, struct env *e)
+eval_internal_sym(struct ast *a, struct env *e)
 {
   if (strcmp(a->v.token->v.str, "def") == 0)
     return eval_def(a, e);
@@ -368,18 +380,18 @@ eval_sym(struct ast *a, struct env *e)
   } else if (strcmp(a->v.token->v.str, "q") == 0) {
     //return make_ast(AST_QUOTE, a->next);
     return a->next;
-  } else {
-    // fprintf(stderr, "Lookup: %s\n", a->v.token->v.str);
-    struct ast *var = lookup(e, a->v.token->v.str);
-    assert(var != NULL);            /* variable found? */
-    return var;
   }
-  /* XXX: nand, eq, streq, symeq, add, sub, div, mul, 
-   *      mod, lt, numeq, num2bool
-   */
   return NULL;
 }
 
+struct ast *
+eval_defined_sym(struct ast *a, struct env *e)
+{
+  struct ast *var = lookup(e, a->v.token->v.str);
+  assert(var != NULL);            /* variable found? */
+  return var;
+}
+
 struct ast *
 eval(struct ast *a, struct env *e)
 {
@@ -390,13 +402,22 @@ eval(struct ast *a, struct env *e)
     if (token_is_num(a->v.token))
       return make_ast(AST_TOK, a->v.token);
     else if (token_is_sym(a->v.token))
-      return eval_sym(a, e);
+      return eval_defined_sym(a, e);
     else if (token_is_str(a->v.token))
       return make_ast(AST_TOK, a->v.token);
     else if (token_is_bool(a->v.token))
       return make_ast(AST_TOK, a->v.token);
   case AST_LIST:
-    return eval(a->v.list, e);
+    /* XXX either it's an internal function, a custom defined function
+    *      or an lambda expression ((lm (x) (* x x)) 2) */
+    assert ((a->v.list->type == AST_TOK &&
+             a->v.list->v.token->type == SYM) ||
+            (a->v.list->type == AST_LIST));
+    if (token_is_internal(a->v.list->v.token))
+      return eval_internal_sym(a->v.list, e);
+    /* else if ((r = eval_defined_function(a->v.list, e)) != NULL) */
+    /*   return r; */
+    assert(0);
   default:
     fprintf(stderr, "%d\n", a->type);
     assert(0);