diff --git a/examples/algorithms/bubble_sort.noja b/examples/algorithms/bubble_sort.noja
index 8dd635c..79f4667 100644
--- a/examples/algorithms/bubble_sort.noja
+++ b/examples/algorithms/bubble_sort.noja
@@ -1,9 +1,4 @@
 
-fun dummy() {}
-Func = type(dummy);
-NFunc = type(print); # The function type is not a built-in at the moment,
-                     # but we can define it manually.
-
 fun copyList(list: List) {
 
 	list2 = [];
@@ -17,10 +12,10 @@ fun copyList(list: List) {
 	return list2;
 }
 
-fun numericLess(a: int | float, b: int | float) 
+fun numericLess(a: Numeric, b: Numeric) 
 	return a < b;
 
-fun bubbleSort(list: List, less: NFunc | Func = numericLess) {
+fun bubbleSort(list: List, less: Callable = numericLess) {
 	
 	list2 = copyList(list);
 
diff --git a/examples/data_structures/queue.noja b/examples/data_structures/queue.noja
deleted file mode 100644
index 4206400..0000000
--- a/examples/data_structures/queue.noja
+++ /dev/null
@@ -1,142 +0,0 @@
-# This script implements a circular queue and
-# its relative tests!
-
-fun newCircularQueue(T: Type = int, max: int = 3) {
-    
-    if T == None:
-        error("Invalid type");
-
-    if max <= 0:
-        error("Maximum queue size must be positive");
-    
-    list = [];
-    i = 0;
-    while i < max: {
-        list[i] = none;
-        i = i+1;
-    }
-
-    return {
-        max: max,
-        head: 0,
-        tail: 0,
-        list: list,
-        type: T
-    };
-}
-
-fun getSize(queue: Map) {
-    
-    size = none;
-    if queue.tail == queue.head: {
-        if queue.list[queue.tail] == none: {
-            size = 0;
-        } else {
-            size = queue.max;
-        }
-    } else if queue.tail < queue.head: {
-        size = queue.head 
-             - queue.tail;
-    } else {
-        size = queue.head 
-             + queue.max 
-             - queue.tail;
-    }
-    return size;
-}
-
-fun append(queue: Map, value) {
-    
-    if type(value) != queue.type:
-        error("Invalid type");
-
-    size = getSize(queue);
-
-    queue.list[queue.head] = value;
-
-    if size == queue.max: {
-        queue.tail = queue.tail+1;
-        if queue.tail == queue.max:
-            queue.tail = 0;
-    }
-
-    queue.head = queue.head+1;
-    if queue.head == queue.max:
-        queue.head = 0;
-}
-
-fun pop(queue: Map) {
-    
-    if getSize(queue) == 0:
-        return none;
-
-    value = queue.list[queue.tail];
-    queue.list[queue.tail] = none;
-
-    queue.tail = queue.tail+1;
-    if queue.tail == queue.max:
-        queue.tail = 0;
-
-    return value;
-}
-
-{
-    utils = import("../utils.noja");
-
-    queue = newCircularQueue(int, 3);
-    assert(getSize(queue) == 0);
-    assert(queue.head == 0);
-    assert(queue.tail == 0);
-
-    append(queue, 1);
-    assert(queue.head == 1);
-    assert(queue.tail == 0);
-    assert(getSize(queue) == 1);
-    assert(utils.compareAny(queue.list, [1, none, none]));
-
-    append(queue, 2);
-    assert(queue.head == 2);
-    assert(queue.tail == 0);
-    assert(getSize(queue) == 2);
-    assert(utils.compareAny(queue.list, [1, 2, none]));
-
-    append(queue, 3);
-    assert(queue.head == 0);
-    assert(queue.tail == 0);
-    assert(getSize(queue) == 3);
-    assert(utils.compareAny(queue.list, [1, 2, 3]));
-
-    append(queue, 4);
-    assert(queue.head == 1);
-    assert(queue.tail == 1);
-    assert(getSize(queue) == 3);
-    assert(utils.compareAny(queue.list, [4, 2, 3]));
-
-    v = pop(queue);
-    assert(v == 2);
-    assert(queue.head == 1);
-    assert(queue.tail == 2);
-    assert(getSize(queue) == 2);
-    assert(utils.compareAny(queue.list, [4, none, 3]));
-
-    v = pop(queue);
-    assert(v == 3);
-    assert(queue.head == 1);
-    assert(queue.tail == 0);
-    assert(getSize(queue) == 1);
-    assert(utils.compareAny(queue.list, [4, none, none]));
-
-    v = pop(queue);
-    assert(v == 4);
-    assert(queue.head == 1);
-    assert(queue.tail == 1);
-    assert(getSize(queue) == 0);
-    assert(utils.compareAny(queue.list, [none, none, none]));
-
-    v = pop(queue);
-    assert(v == none);
-    assert(queue.head == 1);
-    assert(queue.tail == 1);
-    assert(getSize(queue) == 0);
-    assert(utils.compareAny(queue.list, [none, none, none]));
-}
\ No newline at end of file
diff --git a/examples/data_structures/stack.noja b/examples/data_structures/stack.noja
deleted file mode 100644
index d20b8f1..0000000
--- a/examples/data_structures/stack.noja
+++ /dev/null
@@ -1,67 +0,0 @@
-# Implementation of a stack using a linked list.
-
-fun Stack_New(T) {
-	if T == None:
-		return none, "The type can't be None";
-	return { count: 0, head: none, type: T };
-}
-
-fun Stack_Push(stack: Map, value) {
-	
-	assert(stack.type != None);
-
-	if type(value) != stack.type:
-		error("Invalid type");
-
-	node = {prev: none, item: value};
-
-	node.prev = stack.head;
-	stack.head = node;
-	stack.count = stack.count + 1;
-}
-
-fun Stack_Pop(stack: Map) {
-
-	if stack.head == none:
-		return none;
-	
-	value = stack.head.item;
-	stack.head = stack.head.prev;
-	stack.count = stack.count - 1;
-
-	return value;
-}
-
-fun Stack_Print(stack: Map) {
-	print("[");
-	curr = stack.head;
-	while curr != none: {
-		print(curr.item);
-		curr = curr.prev;
-		if curr != none:
-			print(", ");
-	}
-	print("]");
-}
-
-stack = Stack_New(int);
-
-Stack_Push(stack, 1);
-Stack_Push(stack, 2);
-Stack_Push(stack, 3);
-
-Stack_Print(stack);
-print("\n");
-
-x = Stack_Pop(stack);
-y = Stack_Pop(stack);
-z = Stack_Pop(stack);
-w = Stack_Pop(stack);
-
-assert(x == 3);
-assert(y == 2);
-assert(z == 1);
-assert(w == none);
-
-Stack_Print(stack);
-print("\n");
diff --git a/examples/int_to_str.noja b/examples/int_to_str.noja
deleted file mode 100644
index 7fba110..0000000
--- a/examples/int_to_str.noja
+++ /dev/null
@@ -1,65 +0,0 @@
-
-# Shortcuts for some commonly used functions
-chr = string.chr;
-ord = string.ord;
-cat = string.cat;
-
-# Some useful stuff
-Numeric = int | float;
-
-# This function returns the magnitude of the
-# argument and the power of 10 with the same
-# magnitude.
-fun getIntegerMagnitude(n: int) {
-	assert(n >= 0);
-	magn = 0;
-	powr = 1;
-	# Basically grow the power until it's
-	# bigger than the input.
-	while n >= powr * 10: {
-		powr = 10 * powr;
-		magn = 1 + magn;
-	}
-	return magn, powr;
-}
-
-# Stringify a number between 0 and 9.
-fun stringFromDigit(digit: int) {
-	assert(digit >= 0 and digit <= 9);
-	return chr(ord("0") + digit);
-}
-
-fun abs(n: Numeric) {
-	if n < 0:
-		return -n;
-	return n;
-}
-
-# Stringify an unsigned integer
-fun stringFromInteger(n: int) {
-
-	negative = (n < 0);
-	
-	# Get the power of 10 with the
-	# magnitude of the input.
-	_, power = getIntegerMagnitude(n);
-
-	temp = abs(n); # Temporary copy of the input
-	text = ""; # The output we're about to compute
-
-	while power >= 1: {
-		# Pop the leftmost digit from [temp].
-		digit = temp / power; # Get the leftmost digit
-		temp  = temp % power; # Remove it
-
-		# Add the digit to the output.
-		text = cat(text, stringFromDigit(digit));
-
-		# Prep for the next iteration.
-		power = power / 10;
-	}
-
-	if negative:
-		text = cat("-", text);
-	return text;
-}
\ No newline at end of file
diff --git a/examples/json.noja b/examples/json.noja
index 00a44d4..23f8277 100644
--- a/examples/json.noja
+++ b/examples/json.noja
@@ -85,7 +85,7 @@ fun parseArray(scan: Scanner) {
         val, err = parseValue(scan);
         if err != none:
             return none, err;
-        array[count(array)] = val;
+        append(array, val);
 
         char = scan->consumeSpaces();
         if char == ']':
@@ -166,11 +166,6 @@ fun parseNull(scan: Scanner) {
     return none;
 }
 
-fun integerFromDigit(char: String) {
-    assert(isDigit(char));
-    return ord(char) - ord('0');
-}
-
 fun parseNumber(scan: Scanner) {
 
     char = scan->current();
diff --git a/examples/rosetta_code/99_bottles_of_beer.noja b/examples/rosetta_code/99_bottles_of_beer.noja
index aa1a33b..c0f13b7 100644
--- a/examples/rosetta_code/99_bottles_of_beer.noja
+++ b/examples/rosetta_code/99_bottles_of_beer.noja
@@ -18,7 +18,6 @@
 #
 # ==================================
 
-stringFromInteger = import("../int_to_str.noja").stringFromInteger;
 cat = string.cat;
 
 fun verse(n: int)
diff --git a/examples/rosetta_code/arithmetic_and_geometric_mean.noja b/examples/rosetta_code/arithmetic_and_geometric_mean.noja
index df84cfd..2c41a59 100644
--- a/examples/rosetta_code/arithmetic_and_geometric_mean.noja
+++ b/examples/rosetta_code/arithmetic_and_geometric_mean.noja
@@ -1,10 +1,3 @@
-Numeric = int | float;
-
-fun abs(n) {
-	if n < 0:
-		return -n;
-	return n;
-}
 
 # Calculate the arithmetic-geometric mean of x,y.
 fun agm(x: Numeric, y: Numeric, 
diff --git a/examples/scan.noja b/examples/scan.noja
index 24a0779..424b581 100644
--- a/examples/scan.noja
+++ b/examples/scan.noja
@@ -1,15 +1,11 @@
 
-fun dummy() {}
-Func = type(dummy) 
-     | type(print);
-
 Scanner = {
     src: String, 
     i: int,
-    hint: Func,
-    current: Func,
-    consume: Func,
-    consumeSpaces: Func
+    hint: Callable,
+    current: Callable,
+    consume: Callable,
+    consumeSpaces: Callable
 };
 
 fun hint(scan: Scanner, n: int = 1) {
@@ -60,9 +56,3 @@ fun isSpace(c: String)
     return c == ' '
         or c == '\t'
         or c == '\n';
-
-fun min(x, y) {
-    if x < y:
-        return x;
-    return y;
-}
\ No newline at end of file
diff --git a/misc/embedder.c b/misc/embedder.c
index 93e3125..df99914 100644
--- a/misc/embedder.c
+++ b/misc/embedder.c
@@ -58,7 +58,7 @@ int main(int argc, char **argv)
         }
     }
     
-    fprintf(out_stream, "\n};\n");
+    fprintf(out_stream, "\n\t0\n};\n");
 
     fclose(in_stream);
     fclose(out_stream);
diff --git a/src/lib/builtins/start.noja b/src/lib/builtins/start.noja
index d7b72d3..f700859 100644
--- a/src/lib/builtins/start.noja
+++ b/src/lib/builtins/start.noja
@@ -1 +1,88 @@
-name = "Francesco";
\ No newline at end of file
+
+fun abs(n: Numeric) {
+	if n < 0:
+		return -n;
+	return n;
+}
+
+fun min(x, y) {
+    if x < y:
+        return x;
+    return y;
+}
+
+fun max(x, y) {
+    if x > y:
+        return x;
+    return y;
+}
+
+Func  = type(abs);
+NFunc = type(print);
+Numeric = int | float;
+Callable = Func | NFunc;
+Collection = List | Map;
+
+# Stringify a number between 0 and 9.
+fun stringFromDigit(digit: int) {
+	assert(digit >= 0 and digit <= 9);
+	return string.chr(string.ord("0") + digit);
+}
+
+# Stringify an unsigned integer
+fun stringFromInteger(n: int) {
+
+	# This function returns the magnitude of the
+	# argument and the power of 10 with the same
+	# magnitude.
+	fun getIntegerMagnitude(n: int) {
+		assert(n >= 0);
+		magn = 0;
+		powr = 1;
+		# Basically grow the power until it's
+		# bigger than the input.
+		while n >= powr * 10: {
+			powr = 10 * powr;
+			magn = 1 + magn;
+		}
+		return magn, powr;
+	}
+
+	negative = (n < 0);
+	
+	# Get the power of 10 with the
+	# magnitude of the input.
+	_, power = getIntegerMagnitude(n);
+
+	temp = abs(n); # Temporary copy of the input
+	text = ""; # The output we're about to compute
+
+	while power >= 1: {
+		# Pop the leftmost digit from [temp].
+		digit = temp / power; # Get the leftmost digit
+		temp  = temp % power; # Remove it
+
+		# Add the digit to the output.
+		text = string.cat(text, stringFromDigit(digit));
+
+		# Prep for the next iteration.
+		power = power / 10;
+	}
+
+	if negative:
+		text = string.cat("-", text);
+	return text;
+}
+
+fun floatFromInteger(n: int)
+	return 1.0 * n;
+
+fun integerFromDigit(char: String) {
+    res = ord(char) - ord('0');
+    if res < 0 or res > 9:
+    	error("String isn't a digit");
+    return res;
+}
+
+fun append(array: List, item)
+	array[count(array)] = item;
\ No newline at end of file
diff --git a/src/lib/noja.c b/src/lib/noja.c
index baf2fbb..b3e8a7c 100644
--- a/src/lib/noja.c
+++ b/src/lib/noja.c
@@ -82,7 +82,7 @@ static _Bool interpret(Executable *exe)
 
         CompilationErrorType errtyp;
         Executable *prelude_exe = compile(prelude, (Error*) &error, &errtyp);
-        if(exe == NULL) {
+        if(prelude_exe == NULL) {
             const char *errname;
             switch(errtyp) {
                 default:
@@ -109,6 +109,21 @@ static _Bool interpret(Executable *exe)
         }
         Object *noja_bins = rets[0];
 
+        // Need to remake the native built-ins because
+        // running the script invalidated the previous 
+        // pointer.
+        native_bins = Object_NewStaticMap(bins_basic, bins_basic_init, runt, (Error*) &error);
+        if(native_bins == NULL)
+        {
+            assert(error.base.occurred == 1);
+            print_error(NULL, (Error*) &error);
+            RuntimeError_Free(&error);
+            Runtime_Free(runt);
+            Source_Free(prelude);
+            Executable_Free(prelude_exe);
+            return 0;
+        }
+
         Object *all_bins = Object_NewClosure(native_bins, noja_bins, Runtime_GetHeap(runt), (Error*) &error);
         if (all_bins == NULL) {
             print_error(NULL, (Error*) &error);
diff --git a/src/lib/objects/heap.c b/src/lib/objects/heap.c
index a228ded..740c80d 100644
--- a/src/lib/objects/heap.c
+++ b/src/lib/objects/heap.c
@@ -170,6 +170,7 @@ void Heap_Free(Heap *heap)
 			// it now though.
 			Error_Free(&error);
 			Error_Init(&error);
+			// Continue the loop..
 		}
 	}
 
diff --git a/src/lib/objects/o_buffer.c b/src/lib/objects/o_buffer.c
index 6f11fab..95a586f 100644
--- a/src/lib/objects/o_buffer.c
+++ b/src/lib/objects/o_buffer.c
@@ -108,7 +108,7 @@ static _Bool buffer_free(Object *self, Error *error)
 	UNUSED(error);
 
 	BufferObject *buffer = (BufferObject*) self;
-
+	
 	Payload *payload = buffer->payload;
 	ASSERT(payload != NULL && payload->refs > 0);
 
@@ -142,6 +142,7 @@ Object *Object_SliceBuffer(Object *obj, size_t offset, size_t length, Heap *heap
 	if(slice == NULL)
 		return NULL;
 
+	payload->refs++;
 	slice->payload = payload;
 	slice->offset = offset;
 	slice->length = length;
diff --git a/src/lib/objects/o_file.c b/src/lib/objects/o_file.c
index 0b2b9c8..c1b2ed6 100644
--- a/src/lib/objects/o_file.c
+++ b/src/lib/objects/o_file.c
@@ -57,9 +57,9 @@ _Bool Object_IsFile(Object *obj)
 
 FILE *Object_GetStream(Object *obj)
 {
-	if(!Object_IsDir(obj)) {
+	if(!Object_IsFile(obj)) {
 		Error_Panic("%s expected a " TYPENAME_FILE
-			        "object, but an %s was provided", 
+			        " object, but an %s was provided", 
 			        __func__,  Object_GetName(obj));
 		return NULL;
 	}