diff --git a/include/ground.h b/include/ground.h
index 753a553..21b0b4e 100644
--- a/include/ground.h
+++ b/include/ground.h
@@ -336,6 +336,23 @@ struct GroundBytecode {
     GroundBytecodeHeap    heap;
 };
 
+
+// --- Internal Ground components, avoid use outside of Ground ---
+
+enum GroundExecutionResultType {
+    _GER_CONTINUE, _GER_JUMP, _GER_RETURN, _GER_END
+};
+
+struct GroundExecutionResult {
+    enum GroundExecutionResultType type;
+    union {
+        GroundBytecodeValue value;
+        GroundSize line;
+        GroundInt end;
+    } as;
+};
+
+
 // 
 // INTERFACE
 // 
@@ -428,6 +445,8 @@ struct _Ground {
         GroundState       (*State)       (GroundState* in);
 
         GroundIdentifier* (*Identifier) (GroundIdentifier* in);
+
+        GroundBytecodeValue (*BytecodeValue) (GroundBytecodeValue* in);
     } Copy;
 
     struct {
@@ -481,11 +500,11 @@ struct _Ground {
         void         (*save) (GroundBytecode* bytecode, const char* path);
         GroundBytecode (*load) (const char* path);
         struct {
-            void (*execute)  (GroundBytecodeProgram* program, GroundBytecodeHeap* heap);
-            void (*optimise) (GroundBytecodeProgram* program);
+            GroundBytecodeValue (*execute)  (GroundBytecodeProgram* program, GroundBytecodeHeap* heap);
+            void                (*optimise) (GroundBytecodeProgram* program);
         } Program;
         struct {
-            int64_t (*execute) (GroundBytecodeInstruction* instruction, GroundBytecodeHeap* heap);
+            struct GroundExecutionResult (*execute) (GroundBytecodeInstruction* instruction, GroundBytecodeHeap* heap);
         } Instruction;
         struct {
             void         (*set) (GroundBytecodeHeap* heap, GroundSize idx, GroundValue value);
diff --git a/meson.build b/meson.build
index e2bbb59..29c92c7 100644
--- a/meson.build
+++ b/meson.build
@@ -25,6 +25,8 @@ sources = files(
 
     'src/Copy/Identifier.c',
 
+    'src/Copy/BytecodeValue.c',
+
     'src/Free/Function.c',
     'src/Free/List.c',
     'src/Free/Object.c',
diff --git a/src/Bytecode/Instruction/execute.c b/src/Bytecode/Instruction/execute.c
index 28db9bd..3aad2ec 100644
--- a/src/Bytecode/Instruction/execute.c
+++ b/src/Bytecode/Instruction/execute.c
@@ -9,6 +9,11 @@
 #define HEAP_GET(heap, idx) (&(heap)->heap[(idx)])
 #define HEAP_SET(heap, idx, val) ((heap)->heap[(idx)] = (val))
 
+#define CONTINUE    (struct GroundExecutionResult) { _GER_CONTINUE }
+#define JUMP(idx)   (struct GroundExecutionResult) { .type = _GER_JUMP,   .as.line  = idx }
+#define END(res)    (struct GroundExecutionResult) { .type = _GER_END,    .as.end   = res }
+#define RETURN(val) (struct GroundExecutionResult) { .type = _GER_RETURN, .as.value = val }
+
 static void printValue(GroundBytecodeValue* val) {
     switch (val->type.type) {
         case GroundType_Int:
@@ -32,7 +37,7 @@ static void printValue(GroundBytecodeValue* val) {
     }
 }
 
-int64_t _GroundBytecodeInstructionExecute(GroundBytecodeInstruction* instruction, GroundBytecodeHeap* heap) {
+struct GroundExecutionResult _GroundBytecodeInstructionExecute(GroundBytecodeInstruction* instruction, GroundBytecodeHeap* heap) {
 
     static const void* jumpTable[] = {
         &&IF, &&JUMP, &&END, 
@@ -55,67 +60,67 @@ int64_t _GroundBytecodeInstructionExecute(GroundBytecodeInstruction* instruction
     IF: {
         GroundBytecodeValue* cond = HEAP_GET(heap, instruction->args.at[0]);
         if (cond->as.Bool) {
-            return instruction->args.at[1];
+            return JUMP(instruction->args.at[1]);
         }
-        return -1;
+        return CONTINUE;
     }
     JUMP: {
-        return instruction->args.at[0];
+        return JUMP(instruction->args.at[0]);
     }
     END: {
-        return -2;
+        return END( HEAP_GET(heap, instruction->args.at[0])->as.Int );
     }
     INPUT: {
         char* input = linenoise("");
         HEAP_SET(heap, instruction->args.at[0], Ground.New.BytecodeValue(Ground.New.Value.String(Ground.New.String(input))));
         free(input);
-        return -1;
+        return CONTINUE;
     }
     PRINT: {
         for (GroundSize i = 0; i < instruction->args.len; i++) {
             printValue(HEAP_GET(heap, instruction->args.at[i]));
         }
-        return -1;
+        return CONTINUE;
     }
     PRINTLN: {
         for (GroundSize i = 0; i < instruction->args.len; i++) {
             printValue(HEAP_GET(heap, instruction->args.at[i]));
         }
         printf("\n");
-        return -1;
+        return CONTINUE;
     }
     SET: {
         HEAP_SET(heap, instruction->args.at[0], *HEAP_GET(heap, instruction->args.at[1]));
-        return -1;
+        return CONTINUE;
     }
     GETTYPE: {
         Ground.Log.Warning("GETTYPE is deprecated");
-        return -1;
+        return CONTINUE;
     }
     EXISTS: {
         Ground.Log.Warning("EXISTS is deprecated");
-        return -1;
+        return CONTINUE;
     }
     SETLIST: {
-        return -1;
+        return CONTINUE;
     }
     SETLISTAT: {
-        return -1;
+        return CONTINUE;
     }
     GETLISTAT: {
-        return -1;
+        return CONTINUE;
     }
     GETLISTSIZE: {
-        return -1;
+        return CONTINUE;
     }
     LISTAPPEND: {
-        return -1;
+        return CONTINUE;
     }
     GETSTRSIZE: {
-        return -1;
+        return CONTINUE;
     }
     GETSTRCHARAT: {
-        return -1;
+        return CONTINUE;
     }
     ADD: {
         GroundBytecodeValue* final = HEAP_GET(heap, instruction->args.at[2]);
@@ -186,7 +191,7 @@ int64_t _GroundBytecodeInstructionExecute(GroundBytecodeInstruction* instruction
                 break;
             }
         }
-        return -1;
+        return CONTINUE;
     }
     SUBTRACT: {
         GroundBytecodeValue* final = HEAP_GET(heap, instruction->args.at[2]);
@@ -236,7 +241,7 @@ int64_t _GroundBytecodeInstructionExecute(GroundBytecodeInstruction* instruction
                 break;
             }
         }
-        return -1;
+        return CONTINUE;
     }
     MULTIPLY: {
         GroundBytecodeValue* final = HEAP_GET(heap, instruction->args.at[2]);
@@ -286,7 +291,7 @@ int64_t _GroundBytecodeInstructionExecute(GroundBytecodeInstruction* instruction
                 break;
             }
         }
-        return -1;
+        return CONTINUE;
     }
     DIVIDE: {
         GroundBytecodeValue* final = HEAP_GET(heap, instruction->args.at[2]);
@@ -336,7 +341,7 @@ int64_t _GroundBytecodeInstructionExecute(GroundBytecodeInstruction* instruction
                 break;
             }
         }
-        return -1;
+        return CONTINUE;
     }
     EQUAL: {
         GroundBytecodeValue* final = HEAP_GET(heap, instruction->args.at[2]);
@@ -407,7 +412,7 @@ int64_t _GroundBytecodeInstructionExecute(GroundBytecodeInstruction* instruction
                 break;
             }
         }
-        return -1;
+        return CONTINUE;
     }
     INEQUAL: {
         GroundBytecodeValue* final = HEAP_GET(heap, instruction->args.at[2]);
@@ -478,11 +483,11 @@ int64_t _GroundBytecodeInstructionExecute(GroundBytecodeInstruction* instruction
                 break;
             }
         }
-        return -1;
+        return CONTINUE;
     }
     NOT: {
         HEAP_SET(heap, instruction->args.at[1], Ground.New.BytecodeValue(Ground.New.Value.Bool(!HEAP_GET(heap, instruction->args.at[0])->as.Bool)));
-        return -1;
+        return CONTINUE;
     }
     GREATER: {
         GroundBytecodeValue* final = HEAP_GET(heap, instruction->args.at[2]);
@@ -529,7 +534,7 @@ int64_t _GroundBytecodeInstructionExecute(GroundBytecodeInstruction* instruction
                 break;
             }
         }
-        return -1;
+        return CONTINUE;
     }
     LESSER: {
         GroundBytecodeValue* final = HEAP_GET(heap, instruction->args.at[2]);
@@ -576,7 +581,7 @@ int64_t _GroundBytecodeInstructionExecute(GroundBytecodeInstruction* instruction
                 break;
             }
         }
-        return -1;
+        return CONTINUE;
     }
     AND: {
         GroundBytecodeValue* final = HEAP_GET(heap, instruction->args.at[2]);
@@ -585,7 +590,7 @@ int64_t _GroundBytecodeInstructionExecute(GroundBytecodeInstruction* instruction
         
         *final = Ground.New.BytecodeValue(Ground.New.Value.Bool(left->as.Bool && right->as.Bool));
 
-        return -1;
+        return CONTINUE;
     }
     OR: {
         GroundBytecodeValue* final = HEAP_GET(heap, instruction->args.at[2]);
@@ -594,7 +599,7 @@ int64_t _GroundBytecodeInstructionExecute(GroundBytecodeInstruction* instruction
         
         *final = Ground.New.BytecodeValue(Ground.New.Value.Bool(left->as.Bool || right->as.Bool));
 
-        return -1;
+        return CONTINUE;
     }
     XOR: {
         GroundBytecodeValue* final = HEAP_GET(heap, instruction->args.at[2]);
@@ -603,13 +608,13 @@ int64_t _GroundBytecodeInstructionExecute(GroundBytecodeInstruction* instruction
         
         *final = Ground.New.BytecodeValue(Ground.New.Value.Bool(left->as.Bool != right->as.Bool));
 
-        return -1;
+        return CONTINUE;
     }
     NEG: {
-        return -1;
+        return CONTINUE;
     }
     SHIFT: {
-        return -1;
+        return CONTINUE;
     }
     STOI: {
         GroundBytecodeValue* final = HEAP_GET(heap, instruction->args.at[1]);
@@ -624,7 +629,7 @@ int64_t _GroundBytecodeInstructionExecute(GroundBytecodeInstruction* instruction
             Ground.Log.Error("Failed converting string to double");
         }
 
-        return -1;
+        return CONTINUE;
     }
     STOD: {
         GroundBytecodeValue* final = HEAP_GET(heap, instruction->args.at[1]);
@@ -639,7 +644,7 @@ int64_t _GroundBytecodeInstructionExecute(GroundBytecodeInstruction* instruction
             Ground.Log.Error("Failed converting string to double");
         }
 
-        return -1;
+        return CONTINUE;
     }
     ITOC: {
         GroundBytecodeValue* final = HEAP_GET(heap, instruction->args.at[1]);
@@ -647,7 +652,7 @@ int64_t _GroundBytecodeInstructionExecute(GroundBytecodeInstruction* instruction
         
         *final = Ground.New.BytecodeValue(Ground.New.Value.Char((char)in->as.Int));
 
-        return -1;
+        return CONTINUE;
     }
     CTOI: {
         GroundBytecodeValue* final = HEAP_GET(heap, instruction->args.at[1]);
@@ -655,7 +660,7 @@ int64_t _GroundBytecodeInstructionExecute(GroundBytecodeInstruction* instruction
         
         *final = Ground.New.BytecodeValue(Ground.New.Value.Int((int64_t)in->as.Char));
 
-        return -1;
+        return CONTINUE;
     }
     TOSTRING: {
         GroundBytecodeValue* final = HEAP_GET(heap, instruction->args.at[1]);
@@ -682,7 +687,7 @@ int64_t _GroundBytecodeInstructionExecute(GroundBytecodeInstruction* instruction
             }
             case GroundType_String: {
                 *in = Ground.New.BytecodeValue(Ground.New.Value.String(final->as.String));
-                return -1;
+                return CONTINUE;
             }
 
             default: {
@@ -694,76 +699,120 @@ int64_t _GroundBytecodeInstructionExecute(GroundBytecodeInstruction* instruction
 
         *in = Ground.New.BytecodeValue(Ground.New.Value.String(Ground.New.String(buf)));
         
-        return -1;
+        return CONTINUE;
     }
     FUN: {
-        // no-op
-        return -1;
+        // make a copy of the current state and attach it to the function
+        GroundBytecodeFunction* function = &HEAP_GET(heap, instruction->args.at[0])->as.Function;
+
+        if (function->closure == NULL) {}
+
+        return CONTINUE;
     }
     RETURN: {
-        return -1;
+        return RETURN( *HEAP_GET(heap, instruction->args.at[0]) );
     }
     ENDFUN: {
         // no-op
-        return -1;
+        return CONTINUE;
     }
     CALL: {
-        return -1;
+        // call !function $value... &returnIdx
+        GroundBytecodeFunction* function = &HEAP_GET(heap, instruction->args.at[0])->as.Function;
+
+        if (function->isNativeFunction) {
+            // TODO implement calling native functions
+            return CONTINUE;
+        }
+
+        if (function->closure == NULL) {
+            Ground.Log.Error("unexpected NULL closure in Ground.Bytecode.Instruction.execute");
+            Ground.Flags.error = true;
+            return CONTINUE;
+        } 
+
+        // amount of captured variables + amount of function args
+        GroundSize heapSize = function->closure->len + function->args.count;
+
+        GroundBytecodeHeap newHeap = { malloc(sizeof(GroundBytecodeValue) * heapSize), heapSize, heapSize };
+        if (newHeap.heap == NULL) {
+            Ground.Log.Error("malloc failed in Ground.Bytecode.Instruction.execute");
+            Ground.Flags.error = true;
+            return CONTINUE;
+        }
+
+        // load function arguments into the heap        
+        for (GroundSize i = 0; i < function->args.count; i++) {
+            newHeap.heap[i] = Ground.Copy.BytecodeValue(HEAP_GET(heap, i + 1)); // +1 because arg 1 is where fn args start
+        }
+
+        // function arguments are the first indexes, copy after
+        for (GroundSize i = function->args.count; i < newHeap.len; i++) {
+            newHeap.heap[i] = Ground.Copy.BytecodeValue(&function->closure->heap[i]);
+        }
+
+        // Now we run the thingy
+        GroundBytecodeValue result = Ground.Bytecode.Program.execute(function->program.ground, &newHeap);
+
+        // And store the result 
+        HEAP_SET(heap, instruction->args.at[instruction->args.len - 1], result);
+
+        return CONTINUE;
     }
     CALLMETHOD: {
-        return -1;
+        return CONTINUE;
     }
     STRUCT: {
         // no-op
-        return -1;
+        return CONTINUE;
     }
     ENDSTRUCT: {
         // no-op
-        return -1;
+        return CONTINUE;
     }
     INIT: {
-        return -1;
+        return CONTINUE;
     }
     GETFIELD: {
-        return -1;
+        return CONTINUE;
     }
     SETFIELD: {
-        return -1;
+        return CONTINUE;
     }
     USE: {
-        return -1;
+        return CONTINUE;
     }
     EXTERN: {
-        return -1;
+        return CONTINUE;
     }
     CREATELABEL: {
         // no-op
-        return -1;
+        return CONTINUE;
     }
     PAUSE: {
-        return -1;
+        return CONTINUE;
     }
     DROP: {
         GroundBytecodeValue* in = HEAP_GET(heap, instruction->args.at[0]);
         Ground.Free.BytecodeValue(in);
         *in = Ground.New.BytecodeValue(Ground.New.Value.Int(0));
-        return -1;
+        return CONTINUE;
     }
     LICENSE: {
-        return -1;
+        return CONTINUE;
     }
     ERRORCMD: {
-        return -1;
+        return CONTINUE;
     }
     THROW: {
-        return -1;
+        return CONTINUE;
     }
     CATCH: {
-        return -1;
+        return CONTINUE;
     }
 
     Ground.Log.Error("operation fell through in Ground.Instruction.execute()");
     Ground.Flags.error = true;
 
-    return -1;
+    return CONTINUE;
 }
diff --git a/src/Bytecode/Program/execute.c b/src/Bytecode/Program/execute.c
index c7e5ac6..09df625 100644
--- a/src/Bytecode/Program/execute.c
+++ b/src/Bytecode/Program/execute.c
@@ -1,18 +1,22 @@
 #include "../../../include/ground.h"
 #include <stdint.h>
 
-void _GroundBytecodeProgramExecute(GroundBytecodeProgram* program, GroundBytecodeHeap* heap) {
+GroundBytecodeValue _GroundBytecodeProgramExecute(GroundBytecodeProgram* program, GroundBytecodeHeap* heap) {
     GroundSize i = 0;
     while (i < program->len) {
-        int64_t status = Ground.Bytecode.Instruction.execute(&program->at[i], heap);
+        struct GroundExecutionResult status = Ground.Bytecode.Instruction.execute(&program->at[i], heap);
         if (Ground.Flags.error) {
-            return;
+            return Ground.New.BytecodeValue(Ground.New.Value.Int(1));
         }
 
-        switch (status) {
-            case -1: i++; break;
-            case -2: return;
-            default: i = status; break;
+        switch (status.type) {
+
+            case _GER_CONTINUE: i++; break;
+            case _GER_RETURN:   return status.as.value;
+            case _GER_JUMP:     i = status.as.line; break;
+            case _GER_END:      exit(status.as.end);
+
         }
     }
+    return Ground.New.BytecodeValue(Ground.New.Value.Int(0));
 }
diff --git a/src/Copy/BytecodeValue.c b/src/Copy/BytecodeValue.c
new file mode 100644
index 0000000..3cd2a09
--- /dev/null
+++ b/src/Copy/BytecodeValue.c
@@ -0,0 +1,22 @@
+#include "../../include/ground.h"
+
+GroundBytecodeValue _GroundCopyBytecodeValue(GroundBytecodeValue* value) {
+    GroundBytecodeValue newValue = *value;
+    switch (value->type.type) {
+        case GroundType_Int:
+        case GroundType_Double:
+        case GroundType_Bool:
+        case GroundType_Char:
+            break;
+
+        case GroundType_String: {
+            newValue.as.String = Ground.Copy.String(&value->as.String);
+            break;
+        }
+
+        // TODO: Implement copying for everything else 
+        default: break;
+    }
+
+    return newValue;
+}
diff --git a/src/libmain.c b/src/libmain.c
index 28645a5..73eb3e6 100644
--- a/src/libmain.c
+++ b/src/libmain.c
@@ -66,6 +66,8 @@ GroundState _GroundCopyState(GroundState* in);
 
 GroundIdentifier* _GroundCopyIdentifier(GroundIdentifier* identifier);
 
+GroundBytecodeValue _GroundCopyBytecodeValue(GroundBytecodeValue* value);
+
 
 void _GroundListAppend(GroundList* list, GroundValue value);
 
@@ -99,10 +101,10 @@ void _GroundLogWarning(const char* message);
 void _GroundLogPrintErrors();
 
 
-void _GroundBytecodeProgramExecute(GroundBytecodeProgram* program, GroundBytecodeHeap* heap);
+GroundBytecodeValue _GroundBytecodeProgramExecute(GroundBytecodeProgram* program, GroundBytecodeHeap* heap);
 void _GroundBytecodeProgramOptimise(GroundBytecodeProgram* program);
 
-int64_t _GroundBytecodeInstructionExecute(GroundBytecodeInstruction* instruction, GroundBytecodeHeap* heap);
+struct GroundExecutionResult _GroundBytecodeInstructionExecute(GroundBytecodeInstruction* instruction, GroundBytecodeHeap* heap);
 
 void _GroundBytecodeSave(GroundBytecode* bytecode, const char* path);
 GroundBytecode _GroundBytecodeLoad(const char* path);