diff --git a/src/code_defs.h b/src/code_defs.h
index 2961e1c..e569e83 100755
--- a/src/code_defs.h
+++ b/src/code_defs.h
@@ -64,7 +64,7 @@ struct Statement {
       Tag var_type;
     };
     FnSig *func;
-    Tag vtype;
+    void *els; // "Bodge" - pointer to else for if's
   };
 
 };
diff --git a/src/exec_common.h b/src/exec_common.h
index 34efa18..dce68f4 100644
--- a/src/exec_common.h
+++ b/src/exec_common.h
@@ -8,4 +8,6 @@ void runtime_err(char *s);
 
 int evaluate(Value val);
 
+Value is(Tag tag, Value b);
+
 void symbol_map_add_bi(HashMap *map);
diff --git a/src/interpreter.c b/src/interpreter.c
index dfadb3a..19a89c4 100644
--- a/src/interpreter.c
+++ b/src/interpreter.c
@@ -6,6 +6,7 @@
 #include "types.h"
 #include "code_defs.h"
 #include "byte_defs.h"
+#include "exec_common.h"
 
 Value vars[SYMBOL_MAP_S];
 
@@ -31,11 +32,16 @@ Value execute(Statement *stat){
       break;
     case BI_var:
     case BI_let:
+      // Init the relevant value for correct "is"
+      vars[stat->var_id].tag = stat->var_type;
       break;
-    // TODO
     case BI_if:
       if(evaluate(execute(stat->children[0])))
         execute(stat->children[1]);
+      else {
+        if(stat->els)
+          execute(((Statement*)stat->els)->children[0]);
+      }
     case BI_else:
       break;
     case BI_while:
@@ -45,8 +51,8 @@ Value execute(Statement *stat){
     case BI_fn:
     case BI_import:
       break;
-    // TODO
     case BI_is:
+      returnv = is(stat->var_type, execute(stat->children[0]));
       break;
     // TODO
     case BI_cast:
diff --git a/src/parse_utils.c b/src/parse_utils.c
index 096b63b..9306bf4 100644
--- a/src/parse_utils.c
+++ b/src/parse_utils.c
@@ -103,7 +103,7 @@ FnSig bi_sig[] = {
 
 };
 
-Statement *make_operation(i32 type, i32 extrainf, char *name, i32 nparam, ...){
+Statement *make_operation(i32 type, Tag vtype, char *name, i32 nparam, ...){
   Statement *stat = &stack->statements[stack->curr_statement++];
   if(nparam)
     stat->children = malloc(sizeof(void*)*nparam);
@@ -114,10 +114,11 @@ Statement *make_operation(i32 type, i32 extrainf, char *name, i32 nparam, ...){
   va_start(prm, nparam);
   Statement *param = va_arg(prm, Statement*); 
 
-  if(!type){
-    i32 len = strcspn(name, " \t\n");
+  if(!type || type == ST_Call){
+    i32 len = strcspn(name, " \t\n()");
     char *name2 = strndup(name, len);
     MapItem *ret = hashmap_get(&stack->symbol_map, name2);
+    free(name2);
     if(!ret)
       yyerror("Undefined identifer");
     if(nparam > 1 && ret->type != T_fn)
@@ -132,9 +133,13 @@ Statement *make_operation(i32 type, i32 extrainf, char *name, i32 nparam, ...){
       type = ST_Call;
       stat->func = fnsig;
     }
-    if(param->child_n > fnsig->n_param)
-      yyerror("Too many parameters to function");
+    if(nparam){
+      if(param->child_n > fnsig->n_param)
+        yyerror("Too many parameters to function");
+    }
   }
+  if(type == BI_is || type == BI_cast)
+    stat->var_type = vtype;
   stat->type = type;
  
   if(nparam)
diff --git a/src/parser.h b/src/parser.h
index 6b0eb8c..88382de 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -24,7 +24,7 @@ Statement *make_block(Statement *first);
 
 Statement *add_block(Statement *block, Statement *add);
 
-Statement *make_operation(i32 type, i32 extainf, char *str, i32 nparam, ...);
+Statement *make_operation(i32 type, Tag vtype, char *str, i32 nparam, ...);
 
 void set_entry_point(Statement *statement);
 
diff --git a/src/parser.y b/src/parser.y
index 207bb77..6cd49fe 100644
--- a/src/parser.y
+++ b/src/parser.y
@@ -60,7 +60,7 @@ fn_args:
   
 expr:
     '(' G_IDENT ')'                   
-      {$$ = make_operation(ST_Call,0,$2,0);}
+      {$$ = make_operation(ST_Call,ntag,$2,0);}
   | '(' VAR G_IDENT ')'
       { $$ = declare(BI_var,ntag,$3);}
   | '(' VAR type G_IDENT ')'
@@ -78,23 +78,25 @@ expr:
   | '(' LET type G_IDENT expr ')'
       {}
   | '(' IF expr expr_list ')'
-      {$$ = make_operation(BI_if, 0, NULL, 2, $3, $4);}
+      {$$ = make_operation(BI_if, ntag, NULL, 2, $3, $4);}
   | '(' IF expr expr_list ')' '(' ELSE expr_list ')'
-      {Statement *st = make_block(make_operation(BI_if, 0, NULL, 2, $3, $4));
-        $$ = add_block(st, make_operation(BI_else, 0, NULL, 1, $8));
+      {Statement *ifs = make_operation(BI_if, ntag, NULL, 2, $3, $4);
+       Statement *els  = make_operation(BI_else, ntag, NULL, 1, $8);
+       ifs->els = els;
+       $$ = add_block(make_block(ifs),els);
       }
   | '(' WHILE expr expr_list ')'
-      {}
+      {$$ = make_operation(BI_while, ntag, NULL, 2, $3, $4);}
   | '(' FN '(' fn_args ')' expr_list ')'
       {}
   | '(' BLOCK expr_list ')'
       {$$ = $3;}
   | '(' G_IDENT expr_list ')'
-      {$$ = make_operation(ST_None, 0, $2, 1, $3);}
+      {$$ = make_operation(ST_None, ntag, $2, 1, $3);}
   | '(' IS type expr ')'
-      {}
+      {$$ = make_operation(BI_is, $3, NULL, 1, $4);}
   | '(' type expr ')'
-      {}
+      {$$ = make_operation(BI_cast, $2, NULL, 1, $3);}
   | G_IDENT               
       {$$ = variable_get($1);}
   | CST          
diff --git a/src/types.h b/src/types.h
index 11a3916..b68655a 100755
--- a/src/types.h
+++ b/src/types.h
@@ -19,6 +19,8 @@ typedef unsigned int uint;
 #define PACKED __attribute__((__packed__))
 #endif
 
+#define NOPOS __attribute__((designated_init))
+
 enum ValTypes {
   T_null  = 0,
   T_int   = 1,