diff --git a/Makefile b/Makefile
index 2d5e4c8b..9dbb6d05 100644
--- a/Makefile
+++ b/Makefile
@@ -32,7 +32,7 @@ BINDIR=$(PREFIX)/bin
 # TODO - when api is finalized, only export public symbols instead of using rdynamic
 # which exports all symbols. Saves a few KB in binary.
 
-CFLAGS=-std=c99 -Wall -Wextra -Isrc/include -fpic -Os -s
+CFLAGS=-std=c99 -Wall -Wextra -Isrc/include -fpic -O2
 CLIBS=-lm -ldl
 PREFIX=/usr/local
 DST_TARGET=dst
diff --git a/src/core/array.c b/src/core/array.c
index d60a15e9..8338dc9a 100644
--- a/src/core/array.c
+++ b/src/core/array.c
@@ -183,7 +183,7 @@ static int cfun_slice(DstArgs args) {
     int32_t start, end;
     DST_MINARITY(args, 1);
     DST_MAXARITY(args, 3);
-    if (!dst_seq_view(args.v[0], &vals, &len))
+    if (!dst_indexed_view(args.v[0], &vals, &len))
         DST_THROW(args, "expected array|tuple");
     /* Get start */
     if (args.n < 2) {
@@ -231,7 +231,7 @@ static int cfun_concat(DstArgs args) {
                 {
                     int32_t j, len;
                     const Dst *vals;
-                    dst_seq_view(args.v[i], &vals, &len);
+                    dst_indexed_view(args.v[i], &vals, &len);
                     for (j = 0; j < len; j++)
                         dst_array_push(array, vals[j]);
                 }
diff --git a/src/core/asm.c b/src/core/asm.c
index 95cd90a9..1a732666 100644
--- a/src/core/asm.c
+++ b/src/core/asm.c
@@ -554,7 +554,7 @@ static DstAssembleResult dst_asm1(DstAssembler *parent, Dst source, int flags) {
 
     /* Create slot aliases */
     x = dst_get(s, dst_csymbolv("slots"));
-    if (dst_seq_view(x, &arr, &count)) {
+    if (dst_indexed_view(x, &arr, &count)) {
         for (i = 0; i < count; i++) {
             Dst v = arr[i];
             if (dst_checktype(v, DST_TUPLE)) {
@@ -575,7 +575,7 @@ static DstAssembleResult dst_asm1(DstAssembler *parent, Dst source, int flags) {
 
     /* Parse constants */
     x = dst_get(s, dst_csymbolv("constants"));
-    if (dst_seq_view(x, &arr, &count)) {
+    if (dst_indexed_view(x, &arr, &count)) {
         def->constants_length = count;
         def->constants = malloc(sizeof(Dst) * count);
         if (NULL == def->constants) {
@@ -610,7 +610,7 @@ static DstAssembleResult dst_asm1(DstAssembler *parent, Dst source, int flags) {
 
     /* Parse sub funcdefs */
     x = dst_get(s, dst_csymbolv("closures"));
-    if (dst_seq_view(x, &arr, &count)) {
+    if (dst_indexed_view(x, &arr, &count)) {
         int32_t i;
         for (i = 0; i < count; i++) {
             DstAssembleResult subres;
@@ -640,7 +640,7 @@ static DstAssembleResult dst_asm1(DstAssembler *parent, Dst source, int flags) {
 
     /* Parse bytecode and labels */
     x = dst_get(s, dst_csymbolv("bytecode"));
-    if (dst_seq_view(x, &arr, &count)) {
+    if (dst_indexed_view(x, &arr, &count)) {
         /* Do labels and find length */
         int32_t blength = 0;
         for (i = 0; i < count; ++i) {
@@ -696,7 +696,7 @@ static DstAssembleResult dst_asm1(DstAssembler *parent, Dst source, int flags) {
 
     /* Check for source mapping */
     x = dst_get(s, dst_csymbolv("sourcemap"));
-    if (dst_seq_view(x, &arr, &count)) {
+    if (dst_indexed_view(x, &arr, &count)) {
         dst_asm_assert(&a, count == def->bytecode_length, "sourcemap must have the same length as the bytecode");
         def->sourcemap = malloc(sizeof(DstSourceMapping) * count);
         for (i = 0; i < count; i++) {
diff --git a/src/core/compile.c b/src/core/compile.c
index 00a3e7cb..3c42b694 100644
--- a/src/core/compile.c
+++ b/src/core/compile.c
@@ -48,24 +48,6 @@ void dstc_cerror(DstCompiler *c, const char *m) {
     dstc_error(c, dst_cstring(m));
 }
 
-/* Check error */
-int dstc_iserr(DstFopts *opts) {
-    return (opts->compiler->result.status == DST_COMPILE_ERROR);
-}
-
-/* Get the next key in an associative data structure. Used for iterating through an
- * associative data structure. */
-const DstKV *dstc_next(Dst ds, const DstKV *kv) {
-    switch(dst_type(ds)) {
-        default:
-            return NULL;
-        case DST_TABLE:
-            return (const DstKV *) dst_table_next(dst_unwrap_table(ds), kv);
-        case DST_STRUCT:
-            return dst_struct_next(dst_unwrap_struct(ds), kv);
-    }
-}
-
 /* Free a slot */
 void dstc_freeslot(DstCompiler *c, DstSlot s) {
     if (s.flags & (DST_SLOT_CONSTANT | DST_SLOT_REF | DST_SLOT_NAMED)) return;
@@ -318,11 +300,14 @@ DstSlot *dstc_toslots(DstCompiler *c, const Dst *vals, int32_t len) {
 /* Get a bunch of slots for function arguments */
 DstSlot *dstc_toslotskv(DstCompiler *c, Dst ds) {
     DstSlot *ret = NULL;
-    const DstKV *kv = NULL;
     DstFopts subopts = dstc_fopts_default(c);
-    while ((kv = dstc_next(ds, kv))) {
-        dst_v_push(ret, dstc_value(subopts, kv->key));
-        dst_v_push(ret, dstc_value(subopts, kv->value));
+    const DstKV *kvs = NULL;
+    int32_t cap, i, len;
+    dst_dictionary_view(ds, &kvs, &len, &cap);
+    for (i = 0; i < cap; i++) {
+        if (dst_checktype(kvs[i].key, DST_NIL)) continue;
+        dst_v_push(ret, dstc_value(subopts, kvs[i].key));
+        dst_v_push(ret, dstc_value(subopts, kvs[i].value));
     }
     return ret;
 }
@@ -500,7 +485,7 @@ DstSlot dstc_value(DstFopts opts, Dst x) {
     c->recursion_guard--;
 
     /* Guard against previous errors and unbounded recursion */
-    if (dstc_iserr(&opts)) return dstc_cslot(dst_wrap_nil());
+    if (c->result.status == DST_COMPILE_ERROR) return dstc_cslot(dst_wrap_nil());
     if (c->recursion_guard <= 0) {
         dstc_cerror(c, "recursed too deeply");
         return dstc_cslot(dst_wrap_nil());
@@ -509,8 +494,10 @@ DstSlot dstc_value(DstFopts opts, Dst x) {
     /* Macro expand. Also gets possible special form and
      * refines source mapping cursor if possible. */
     const DstSpecial *spec = NULL;
-    int macroi = DST_RECURSION_GUARD;
-    while (macroi && !dstc_iserr(&opts) && macroexpand1(c, x, &x, &spec))
+    int macroi = DST_MAX_MACRO_EXPAND;
+    while (macroi &&
+            c->result.status != DST_COMPILE_ERROR &&
+            macroexpand1(c, x, &x, &spec))
         macroi--;
     if (macroi == 0) {
         dstc_cerror(c, "recursed too deeply in macro expansion");
@@ -559,13 +546,11 @@ DstSlot dstc_value(DstFopts opts, Dst x) {
         }
     }
 
-    if (dstc_iserr(&opts)) {
+    if (c->result.status == DST_COMPILE_ERROR)
         return dstc_cslot(dst_wrap_nil());
-    }
     c->current_mapping = last_mapping;
-    if (opts.flags & DST_FOPTS_TAIL) {
+    if (opts.flags & DST_FOPTS_TAIL)
         ret = dstc_return(opts.compiler, ret);
-    }
     if (opts.flags & DST_FOPTS_HINT) {
         dstc_copy(opts.compiler, opts.hint, ret);
         ret = opts.hint;
diff --git a/src/core/compile.h b/src/core/compile.h
index 44cc1cd7..6cbff2af 100644
--- a/src/core/compile.h
+++ b/src/core/compile.h
@@ -175,12 +175,6 @@ const DstFunOptimizer *dstc_funopt(uint32_t flags);
 /* Get a special. Return NULL if none exists */
 const DstSpecial *dstc_special(const uint8_t *name);
 
-/* Check error */
-int dstc_iserr(DstFopts *opts);
-
-/* Helper for iterating tables and structs */
-const DstKV *dstc_next(Dst ds, const DstKV *kv);
-
 void dstc_freeslot(DstCompiler *c, DstSlot s);
 void dstc_nameslot(DstCompiler *c, const uint8_t *sym, DstSlot s);
 DstSlot dstc_farslot(DstCompiler *c);
diff --git a/src/core/specials.c b/src/core/specials.c
index 766cf106..55f3b49c 100644
--- a/src/core/specials.c
+++ b/src/core/specials.c
@@ -57,7 +57,7 @@ static int destructure(DstCompiler *c,
             {
                 int32_t i, len;
                 const Dst *values;
-                dst_seq_view(left, &values, &len);
+                dst_indexed_view(left, &values, &len);
                 for (i = 0; i < len; i++) {
                     DstSlot nextright = dstc_farslot(c);
                     Dst subval = values[i];
@@ -75,12 +75,15 @@ static int destructure(DstCompiler *c,
         case DST_TABLE:
         case DST_STRUCT:
             {
-                const DstKV *kv = NULL;
-                while ((kv = dstc_next(left, kv))) {
+                const DstKV *kvs = NULL;
+                int32_t i, cap, len;
+                dst_dictionary_view(left, &kvs, &len, &cap);
+                for (i = 0; i < cap; i++) {
+                    if (dst_checktype(kvs[i].key, DST_NIL)) continue;
                     DstSlot nextright = dstc_farslot(c);
-                    DstSlot k = dstc_value(dstc_fopts_default(c), kv->key);
+                    DstSlot k = dstc_value(dstc_fopts_default(c), kvs[i].key);
                     dstc_emit_sss(c, DOP_GET, nextright, right, k, 1);
-                    if (destructure(c, kv->value, nextright, leaf, attr))
+                    if (destructure(c, kvs[i].value, nextright, leaf, attr))
                         dstc_freeslot(c, nextright);
                 }
             }
@@ -190,7 +193,8 @@ DstSlot dstc_var(DstFopts opts, int32_t argn, const Dst *argv) {
     DstCompiler *c = opts.compiler;
     Dst head;
     DstSlot ret = dohead(c, opts, &head, argn, argv);
-    if (dstc_iserr(&opts)) return dstc_cslot(dst_wrap_nil());
+    if (c->result.status == DST_COMPILE_ERROR)
+        return dstc_cslot(dst_wrap_nil());
     if (destructure(c, argv[0], ret, varleaf, handleattr(c, argn, argv)))
         dstc_freeslot(c, ret);
     return dstc_cslot(dst_wrap_nil());
@@ -223,7 +227,8 @@ DstSlot dstc_def(DstFopts opts, int32_t argn, const Dst *argv) {
     Dst head;
     opts.flags &= ~DST_FOPTS_HINT;
     DstSlot ret = dohead(c, opts, &head, argn, argv);
-    if (dstc_iserr(&opts)) return dstc_cslot(dst_wrap_nil());
+    if (c->result.status == DST_COMPILE_ERROR)
+        return dstc_cslot(dst_wrap_nil());
     if (destructure(c, argv[0], ret, defleaf, handleattr(c, argn, argv)))
         dstc_freeslot(c, ret);
     return dstc_cslot(dst_wrap_nil());
@@ -454,7 +459,7 @@ DstSlot dstc_fn(DstFopts opts, int32_t argn, const Dst *argv) {
         goto error;
     }
     paramv = argv[parami];
-    if (dst_seq_view(paramv, &params, &paramcount)) {
+    if (dst_indexed_view(paramv, &params, &paramcount)) {
         int32_t i;
         for (i = 0; i < paramcount; i++) {
             Dst param = params[i];
@@ -494,7 +499,7 @@ DstSlot dstc_fn(DstFopts opts, int32_t argn, const Dst *argv) {
     } else for (argi = parami + 1; argi < argn; argi++) {
         subopts.flags = (argi == (argn - 1)) ? DST_FOPTS_TAIL : DST_FOPTS_DROP;
         dstc_value(subopts, argv[argi]);
-        if (dstc_iserr(&opts))
+        if (c->result.status == DST_COMPILE_ERROR)
             goto error2;
     }
 
diff --git a/src/core/string.c b/src/core/string.c
index 72eb597b..0d272644 100644
--- a/src/core/string.c
+++ b/src/core/string.c
@@ -937,7 +937,7 @@ static int cfun_join(DstArgs args) {
     for (i = 0; i < partslen; i++) {
         const uint8_t *chunk;
         int32_t chunklen = 0;
-        if (!dst_chararray_view(parts[i], &chunk, &chunklen)) {
+        if (!dst_bytes_view(parts[i], &chunk, &chunklen)) {
             DST_THROW(args, "expected string|symbol|buffer");
         }
         if (i) finallen += joinerlen;
@@ -951,7 +951,7 @@ static int cfun_join(DstArgs args) {
             memcpy(out, joiner, joinerlen);
             out += joinerlen;
         }
-        dst_chararray_view(parts[i], &chunk, &chunklen);
+        dst_bytes_view(parts[i], &chunk, &chunklen);
         memcpy(out, chunk, chunklen);
         out += chunklen;
     }
diff --git a/src/core/tuple.c b/src/core/tuple.c
index 400e6192..62afbb70 100644
--- a/src/core/tuple.c
+++ b/src/core/tuple.c
@@ -44,7 +44,7 @@ const Dst *dst_tuple_end(Dst *tuple) {
 }
 
 /* Build a tuple with n values */
-const Dst *dst_tuple_n(Dst *values, int32_t n) {
+const Dst *dst_tuple_n(const Dst *values, int32_t n) {
     Dst *t = dst_tuple_begin(n);
     memcpy(t, values, sizeof(Dst) * n);
     return dst_tuple_end(t);
@@ -97,7 +97,7 @@ static int cfun_slice(DstArgs args) {
     Dst *ret;
     int32_t start, end;
     DST_MINARITY(args, 1);
-    if (!dst_seq_view(args.v[0], &vals, &len)) DST_THROW(args, "expected array/tuple");
+    if (!dst_indexed_view(args.v[0], &vals, &len)) DST_THROW(args, "expected array/tuple");
     /* Get start */
     if (args.n < 2) {
         start = 0;
@@ -133,7 +133,7 @@ static int cfun_prepend(DstArgs args) {
     int32_t len;
     Dst *n;
     DST_FIXARITY(args, 2);
-    if (!dst_seq_view(args.v[0], &t, &len)) DST_THROW(args, "expected tuple/array");
+    if (!dst_indexed_view(args.v[0], &t, &len)) DST_THROW(args, "expected tuple/array");
     n = dst_tuple_begin(len + 1);
     memcpy(n + 1, t, sizeof(Dst) * len);
     n[0] = args.v[1];
@@ -145,7 +145,7 @@ static int cfun_append(DstArgs args) {
     int32_t len;
     Dst *n;
     DST_FIXARITY(args, 2);
-    if (!dst_seq_view(args.v[0], &t, &len)) DST_THROW(args, "expected tuple/array");
+    if (!dst_indexed_view(args.v[0], &t, &len)) DST_THROW(args, "expected tuple/array");
     n = dst_tuple_begin(len + 1);
     memcpy(n, t, sizeof(Dst) * len);
     n[len] = args.v[1];
diff --git a/src/core/util.c b/src/core/util.c
index a2d5e123..9fe07737 100644
--- a/src/core/util.c
+++ b/src/core/util.c
@@ -202,7 +202,7 @@ DstTable *dst_env_arg(DstArgs args) {
 
 /* Read both tuples and arrays as c pointers + int32_t length. Return 1 if the
  * view can be constructed, 0 if an invalid type. */
-int dst_seq_view(Dst seq, const Dst **data, int32_t *len) {
+int dst_indexed_view(Dst seq, const Dst **data, int32_t *len) {
     if (dst_checktype(seq, DST_ARRAY)) {
         *data = dst_unwrap_array(seq)->data;
         *len = dst_unwrap_array(seq)->count;
@@ -217,7 +217,7 @@ int dst_seq_view(Dst seq, const Dst **data, int32_t *len) {
 
 /* Read both strings and buffer as unsigned character array + int32_t len.
  * Returns 1 if the view can be constructed and 0 if the type is invalid. */
-int dst_chararray_view(Dst str, const uint8_t **data, int32_t *len) {
+int dst_bytes_view(Dst str, const uint8_t **data, int32_t *len) {
     if (dst_checktype(str, DST_STRING) || dst_checktype(str, DST_SYMBOL)) {
         *data = dst_unwrap_string(str);
         *len = dst_string_length(dst_unwrap_string(str));
@@ -233,7 +233,7 @@ int dst_chararray_view(Dst str, const uint8_t **data, int32_t *len) {
 /* Read both structs and tables as the entries of a hashtable with
  * identical structure. Returns 1 if the view can be constructed and
  * 0 if the type is invalid. */
-int dst_hashtable_view(Dst tab, const DstKV **data, int32_t *len, int32_t *cap) {
+int dst_dictionary_view(Dst tab, const DstKV **data, int32_t *len, int32_t *cap) {
     if (dst_checktype(tab, DST_TABLE)) {
         *data = dst_unwrap_table(tab)->data;
         *cap = dst_unwrap_table(tab)->capacity;
diff --git a/src/core/vm.c b/src/core/vm.c
index 0a49455b..fbac0e2d 100644
--- a/src/core/vm.c
+++ b/src/core/vm.c
@@ -708,7 +708,7 @@ static void *op_lookup[255] = {
     {
         const Dst *vals;
         int32_t len;
-        if (dst_seq_view(stack[oparg(1, 0xFFFFFF)], &vals, &len)) {
+        if (dst_indexed_view(stack[oparg(1, 0xFFFFFF)], &vals, &len)) {
             dst_fiber_pushn(fiber, vals, len);
         } else {
             retreg = stack[oparg(1, 0xFFFFFF)];
diff --git a/src/include/dst/dst.h b/src/include/dst/dst.h
index 754b8797..65dce48c 100644
--- a/src/include/dst/dst.h
+++ b/src/include/dst/dst.h
@@ -136,13 +136,21 @@ extern "C" {
 /* Maximum depth to follow table prototypes before giving up and returning nil. */
 #define DST_MAX_PROTO_DEPTH 200
 
+/* Maximum depth to follow table prototypes before giving up and returning nil. */
+#define DST_MAX_MACRO_EXPAND 200
+
 /* Define max stack size for stacks before raising a stack overflow error.
  * If this is not defined, fiber stacks can grow without limit (until memory
  * runs out) */
 #define DST_STACK_MAX 8192
 
-/* Use nanboxed values - uses 8 bytes per value instead of 12 or 16. */
+/* Use nanboxed values - uses 8 bytes per value instead of 12 or 16.
+ * To turn of nanboxing, for debugging purposes or for certain
+ * architectures (Nanboxing only tested on x86 and x64), comment out
+ * the DST_NANBOX define.*/
 #define DST_NANBOX
+
+/* Further refines the type of nanboxing to use. */
 #define DST_NANBOX_47
 
 /* Alignment for pointers */
@@ -895,7 +903,7 @@ int dst_buffer_push_u64(DstBuffer *buffer, uint64_t x);
 #define dst_tuple_sm_col(t) ((dst_tuple_raw(t)[3]))
 Dst *dst_tuple_begin(int32_t length);
 const Dst *dst_tuple_end(Dst *tuple);
-const Dst *dst_tuple_n(Dst *values, int32_t n);
+const Dst *dst_tuple_n(const Dst *values, int32_t n);
 int dst_tuple_equal(const Dst *lhs, const Dst *rhs);
 int dst_tuple_compare(const Dst *lhs, const Dst *rhs);
 
@@ -965,9 +973,9 @@ DstFiber *dst_fiber(DstFunction *callee, int32_t capacity);
 #define dst_fiber_status(f) (((f)->flags & DST_FIBER_STATUS_MASK) >> DST_FIBER_STATUS_OFFSET)
 
 /* Treat similar types through uniform interfaces for iteration */
-int dst_seq_view(Dst seq, const Dst **data, int32_t *len);
-int dst_chararray_view(Dst str, const uint8_t **data, int32_t *len);
-int dst_hashtable_view(Dst tab, const DstKV **data, int32_t *len, int32_t *cap);
+int dst_indexed_view(Dst seq, const Dst **data, int32_t *len);
+int dst_bytes_view(Dst str, const uint8_t **data, int32_t *len);
+int dst_dictionary_view(Dst tab, const DstKV **data, int32_t *len, int32_t *cap);
 
 /* Abstract */
 #define dst_abstract_header(u) ((DstAbstractHeader *)(u) - 1)
@@ -1107,14 +1115,14 @@ int dst_lib_compile(DstArgs args);
 
 #define DST_ARG_BYTES(DESTBYTES, DESTLEN, A, N) do {\
     if ((A).n <= (N)) return dst_typemany_err(A, N, DST_TFLAG_BYTES);\
-    if (!dst_chararray_view((A).v[(N)], &(DESTBYTES), &(DESTLEN))) {\
+    if (!dst_bytes_view((A).v[(N)], &(DESTBYTES), &(DESTLEN))) {\
         return dst_typemany_err(A, N, DST_TFLAG_BYTES);\
     }\
 } while (0)
 
 #define DST_ARG_INDEXED(DESTVALS, DESTLEN, A, N) do {\
     if ((A).n <= (N)) return dst_typemany_err(A, N, DST_TFLAG_INDEXED);\
-    if (!dst_seq_view((A).v[(N)], &(DESTVALS), &(DESTLEN))) {\
+    if (!dst_indexed_view((A).v[(N)], &(DESTVALS), &(DESTLEN))) {\
         return dst_typemany_err(A, N, DST_TFLAG_INDEXED);\
     }\
 } while (0)
diff --git a/test/suite1.dst b/test/suite1.dst
index 9187f4f6..8ecdc21e 100644
--- a/test/suite1.dst
+++ b/test/suite1.dst
@@ -194,4 +194,8 @@
 
 (assert (= 7 (case :a :b 5 :c 6 :u 10 7)), "case with default")
 
+# Testing the loop and for macros
+(def xs (apply1 tuple (for [x :range [0 10] :when (even? x)] (tuple (/ x 2) x))))
+(assert (= xs '((0 0) (1 2) (2 4) (3 6) (4 8))) "for macro 1")
+
 (end-suite)