diff --git a/include/tlibc/collections/Array.h b/include/tlibc/collections/Array.h
index 737c184..9b08cd8 100755
--- a/include/tlibc/collections/Array.h
+++ b/include/tlibc/collections/Array.h
@@ -1,57 +1,62 @@
 #pragma once
 #include "../std.h"
 
-#define Array(T) Array_
+/*
+Pointer and length.
+Can be initialized with {0}.
+*/
 
-typedef struct Array_ {
-    void* data;
-    u32 size;
-} Array_;
+#define Array(T) Array_##T
 
-/// creates Array_ from self const array
-#define ARRAY(T, A...) Array_construct_size(((T[])A), sizeof((T[])A))
+/// create Array(T) from array initializer list ({ a, b, c })
+#define ARRAY(T, A...) ((Array(T)){ .data = ((T[])A), .len = sizeof((T[])A) / sizeof(T) })
 
-#define Array_construct(DATA, T, COUNT) Array_construct_size(DATA, (COUNT) * sizeof(T))
-#define Array_construct_size(DATA, LEN) ((Array_){ .data = (DATA), .size = (LEN) })
+#define Array_declare(T) \
+typedef struct Array(T) { \
+    T* data; \
+    u32 len; \
+} Array(T); \
+ \
+static inline Array(T) Array_##T##_construct(T* data, u32 len) { \
+    return (Array(T)){ .data = data, .len = len }; \
+} \
+ \
+static inline Array(T) Array_##T##_alloc(u32 len){ \
+    if(len == 0) \
+        return Array_##T##_construct(NULL, 0); \
+    return Array_##T##_construct(malloc(len * sizeof(T)), len); \
+} \
+ \
+static inline void Array_##T##_realloc(Array(T)* self, u32 new_len){ \
+    self->data = (T*)realloc(self->data, new_len * sizeof(T)); \
+    self->len = new_len; \
+} \
+ \
+static inline Array(T) Array_##T##_copy(const Array(T) src){ \
+    Array(T) copy = Array_##T##_alloc(src.len); \
+    if(copy.data != NULL) \
+        memcpy(copy.data, src.data, src.len * sizeof(T)); \
+    return copy; \
+} \
+ \
+static inline void Array_##T##_destroy(Array(T)* self){ \
+    if(!self) \
+        return; \
+    free(self->data); \
+} \
+ \
+static inline void Array_##T##_memset(Array(T)* self, u32 value){ \
+    memset(self->data, value, self->len * sizeof(T)); \
+} \
+ \
+/* @return self[0..i-1] */ \
+static inline Array(T) Array_##T##_sliceTo(const Array(T) src, u32 i){ \
+    return Array_##T##_construct(src.data, i); \
+} \
+ \
+/* @return self[i...] */ \
+static inline Array(T) Array_##T##_sliceFrom(const Array(T) src, u32 i){ \
+    return Array_##T##_construct(src.data + i, src.len - i); \
+} \
 
-#define Array_null Array_construct_size(NULL, 0)
-
-#define Array_alloc(T, COUNT) Array_alloc_size((COUNT) * sizeof(T))
-static inline Array_ Array_alloc_size(u32 size){
-    if(size == 0)
-        return Array_null;
-    return Array_construct_size(malloc(size), size);
-}
-
-#define Array_realloc(SELF, T, COUNT) Array_realloc_size(SELF, (COUNT) * sizeof(T))
-
-static inline void Array_realloc_size(Array_* self, u32 new_size){
-    self->data = realloc(self->data, new_size);
-    self->size = new_size;
-}
-
-static inline Array_ Array_copy(const Array_ self){
-    Array_ copy = Array_alloc_size(self.size);
-    if(copy.data != NULL)
-        memcpy(copy.data, self.data, self.size);
-    return copy;
-}
-
-static inline void Array_free(Array_ self){
-    free(self.data);
-}
-
-#define Array_len(SELF, T) (SELF.size / sizeof(T))
-#define Array_memset(SELF, VAL) memset(SELF.data, VAL, SELF.size)
-
-#define struct_castTo_Array(STRUCT_PTR) Array_construct_size((STRUCT_PTR), sizeof(*STRUCT_PTR))
-
-///@return self[0..i-1]
-static inline Array(u8) Array_sliceTo(const Array(u8) self, u32 i){
-    return Array_construct_size(self.data, i);
-}
-
-///@return self[i...]
-static inline Array(u8) Array_sliceFrom(const Array(u8) self, u32 i){
-    return Array_construct_size((u8*)self.data + i, self.size - i);
-}
+#define struct_castTo_Array_u8(STRUCT_PTR) Array_u8_construct((void*)(STRUCT_PTR), sizeof(*STRUCT_PTR))
diff --git a/include/tlibc/collections/Array_impl/Array_char.h b/include/tlibc/collections/Array_impl/Array_char.h
new file mode 100644
index 0000000..0aefc70
--- /dev/null
+++ b/include/tlibc/collections/Array_impl/Array_char.h
@@ -0,0 +1,2 @@
+#pragma once
+Array_declare(char);
diff --git a/include/tlibc/collections/Array_impl/Array_f32.h b/include/tlibc/collections/Array_impl/Array_f32.h
new file mode 100644
index 0000000..ec2e841
--- /dev/null
+++ b/include/tlibc/collections/Array_impl/Array_f32.h
@@ -0,0 +1,2 @@
+#pragma once
+Array_declare(f32);
diff --git a/include/tlibc/collections/Array_impl/Array_f64.h b/include/tlibc/collections/Array_impl/Array_f64.h
new file mode 100644
index 0000000..509be7d
--- /dev/null
+++ b/include/tlibc/collections/Array_impl/Array_f64.h
@@ -0,0 +1,2 @@
+#pragma once
+Array_declare(f64);
diff --git a/include/tlibc/collections/Array_impl/Array_i16.h b/include/tlibc/collections/Array_impl/Array_i16.h
new file mode 100644
index 0000000..a603748
--- /dev/null
+++ b/include/tlibc/collections/Array_impl/Array_i16.h
@@ -0,0 +1,2 @@
+#pragma once
+Array_declare(i16);
diff --git a/include/tlibc/collections/Array_impl/Array_i32.h b/include/tlibc/collections/Array_impl/Array_i32.h
new file mode 100644
index 0000000..6cf6f7b
--- /dev/null
+++ b/include/tlibc/collections/Array_impl/Array_i32.h
@@ -0,0 +1,2 @@
+#pragma once
+Array_declare(i32);
diff --git a/include/tlibc/collections/Array_impl/Array_i64.h b/include/tlibc/collections/Array_impl/Array_i64.h
new file mode 100644
index 0000000..0c0e567
--- /dev/null
+++ b/include/tlibc/collections/Array_impl/Array_i64.h
@@ -0,0 +1,2 @@
+#pragma once
+Array_declare(i64);
diff --git a/include/tlibc/collections/Array_impl/Array_i8.h b/include/tlibc/collections/Array_impl/Array_i8.h
new file mode 100644
index 0000000..47851e7
--- /dev/null
+++ b/include/tlibc/collections/Array_impl/Array_i8.h
@@ -0,0 +1,2 @@
+#pragma once
+Array_declare(i8);
diff --git a/include/tlibc/collections/Array_impl/Array_u16.h b/include/tlibc/collections/Array_impl/Array_u16.h
new file mode 100644
index 0000000..6b944ac
--- /dev/null
+++ b/include/tlibc/collections/Array_impl/Array_u16.h
@@ -0,0 +1,2 @@
+#pragma once
+Array_declare(u16);
diff --git a/include/tlibc/collections/Array_impl/Array_u32.h b/include/tlibc/collections/Array_impl/Array_u32.h
new file mode 100644
index 0000000..d9b07f3
--- /dev/null
+++ b/include/tlibc/collections/Array_impl/Array_u32.h
@@ -0,0 +1,2 @@
+#pragma once
+Array_declare(u32);
diff --git a/include/tlibc/collections/Array_impl/Array_u64.h b/include/tlibc/collections/Array_impl/Array_u64.h
new file mode 100644
index 0000000..65edd5d
--- /dev/null
+++ b/include/tlibc/collections/Array_impl/Array_u64.h
@@ -0,0 +1,2 @@
+#pragma once
+Array_declare(u64);
diff --git a/include/tlibc/collections/Array_impl/Array_u8.h b/include/tlibc/collections/Array_impl/Array_u8.h
new file mode 100644
index 0000000..f40f7f7
--- /dev/null
+++ b/include/tlibc/collections/Array_impl/Array_u8.h
@@ -0,0 +1,2 @@
+#pragma once
+Array_declare(u8);
diff --git a/include/tlibc/collections/HashMap.h b/include/tlibc/collections/HashMap.h
index 6e2d5c8..6e9cf29 100755
--- a/include/tlibc/collections/HashMap.h
+++ b/include/tlibc/collections/HashMap.h
@@ -1,7 +1,6 @@
 #pragma once
 #include "../std.h"
 #include "../string/str.h"
-#include "Array.h"
 #include "List.h"
 
 typedef struct HashMapKeyHash {
@@ -9,9 +8,11 @@ typedef struct HashMapKeyHash {
     u32 hash;
 } HashMapKeyHash;
 
+List_declare(HashMapKeyHash);
+
 typedef struct HashMapBucket {
     List(HashMapKeyHash) key_hash_list;
-    List(T) value_list;
+    List_ value_list;
 } HashMapBucket;
 
 #define HashMap(T) HashMap_
diff --git a/include/tlibc/collections/LList.h b/include/tlibc/collections/LList.h
index 99a7bb2..c5fafe4 100644
--- a/include/tlibc/collections/LList.h
+++ b/include/tlibc/collections/LList.h
@@ -2,7 +2,8 @@
 #include "../std.h"
 
 /*
-Doubly linked list
+Doubly linked list.
+Can be initialized with {0}.
 */
 
 #define LLNode(T) LLNode_##T
diff --git a/include/tlibc/collections/LList_impl/LList_char.h b/include/tlibc/collections/LList_impl/LList_char.h
new file mode 100644
index 0000000..8cf69ef
--- /dev/null
+++ b/include/tlibc/collections/LList_impl/LList_char.h
@@ -0,0 +1,2 @@
+#pragma once
+LList_declare(char);
diff --git a/include/tlibc/collections/LList_impl/LList_f32.h b/include/tlibc/collections/LList_impl/LList_f32.h
new file mode 100644
index 0000000..0843953
--- /dev/null
+++ b/include/tlibc/collections/LList_impl/LList_f32.h
@@ -0,0 +1,2 @@
+#pragma once
+LList_declare(f32);
diff --git a/include/tlibc/collections/LList_impl/LList_f64.h b/include/tlibc/collections/LList_impl/LList_f64.h
new file mode 100644
index 0000000..7111038
--- /dev/null
+++ b/include/tlibc/collections/LList_impl/LList_f64.h
@@ -0,0 +1,2 @@
+#pragma once
+LList_declare(f64);
diff --git a/include/tlibc/collections/LList_impl/LList_i16.h b/include/tlibc/collections/LList_impl/LList_i16.h
new file mode 100644
index 0000000..4d23da6
--- /dev/null
+++ b/include/tlibc/collections/LList_impl/LList_i16.h
@@ -0,0 +1,2 @@
+#pragma once
+LList_declare(i16);
diff --git a/include/tlibc/collections/LList_impl/LList_i32.h b/include/tlibc/collections/LList_impl/LList_i32.h
new file mode 100644
index 0000000..f5393cf
--- /dev/null
+++ b/include/tlibc/collections/LList_impl/LList_i32.h
@@ -0,0 +1,2 @@
+#pragma once
+LList_declare(i32);
diff --git a/include/tlibc/collections/LList_impl/LList_i64.h b/include/tlibc/collections/LList_impl/LList_i64.h
new file mode 100644
index 0000000..2f3397a
--- /dev/null
+++ b/include/tlibc/collections/LList_impl/LList_i64.h
@@ -0,0 +1,2 @@
+#pragma once
+LList_declare(i64);
diff --git a/include/tlibc/collections/LList_impl/LList_i8.h b/include/tlibc/collections/LList_impl/LList_i8.h
new file mode 100644
index 0000000..0a60b1e
--- /dev/null
+++ b/include/tlibc/collections/LList_impl/LList_i8.h
@@ -0,0 +1,2 @@
+#pragma once
+LList_declare(i8);
diff --git a/include/tlibc/collections/LList_impl/LList_u16.h b/include/tlibc/collections/LList_impl/LList_u16.h
new file mode 100644
index 0000000..b969beb
--- /dev/null
+++ b/include/tlibc/collections/LList_impl/LList_u16.h
@@ -0,0 +1,2 @@
+#pragma once
+LList_declare(u16);
diff --git a/include/tlibc/collections/LList_impl/LList_u32.h b/include/tlibc/collections/LList_impl/LList_u32.h
new file mode 100644
index 0000000..3d5a966
--- /dev/null
+++ b/include/tlibc/collections/LList_impl/LList_u32.h
@@ -0,0 +1,2 @@
+#pragma once
+LList_declare(u32);
diff --git a/include/tlibc/collections/LList_impl/LList_u64.h b/include/tlibc/collections/LList_impl/LList_u64.h
new file mode 100644
index 0000000..cca09d4
--- /dev/null
+++ b/include/tlibc/collections/LList_impl/LList_u64.h
@@ -0,0 +1,2 @@
+#pragma once
+LList_declare(u64);
diff --git a/include/tlibc/collections/LList_impl/LList_u8.h b/include/tlibc/collections/LList_impl/LList_u8.h
new file mode 100644
index 0000000..2fbb1dc
--- /dev/null
+++ b/include/tlibc/collections/LList_impl/LList_u8.h
@@ -0,0 +1,2 @@
+#pragma once
+LList_declare(u8);
diff --git a/include/tlibc/collections/List.h b/include/tlibc/collections/List.h
index f7f76f8..9824fdf 100755
--- a/include/tlibc/collections/List.h
+++ b/include/tlibc/collections/List.h
@@ -1,44 +1,89 @@
 #pragma once
 #include "../std.h"
 
-#define List(T) List_
+/*
+Dynamic array.
+CAN NOT be initialized with {0}.
+*/
+
+#define List(T) List_##T
+
+#define List_declare(T) \
+typedef struct List(T) { \
+    T* data; \
+    u32 len; \
+    u32 capacity; \
+    u32 elem_t_size; \
+} List(T); \
+ \
+static inline List(T) List_##T##_construct(T* data_ptr, u32 occupied_len, u32 capacity) { \
+    return (List(T)){ \
+        .data = data_ptr, \
+        .len = occupied_len, \
+        .capacity = capacity, \
+        .elem_t_size = sizeof(T) \
+    }; \
+} \
+ \
+static inline List(T) List_##T##_alloc(u32 initial_capacity) { \
+    List_ l = _List_alloc(initial_capacity, sizeof(T)); \
+    return *(List(T)*)(void*)&l; \
+} \
+ \
+static inline List(T) List_##T##_copy(const List(T)* src) { \
+    List_ l = _List_copy((void*)src); \
+    return *(List(T)*)(void*)&l; \
+} \
+ \
+static inline void List_##T##_destroy(List(T)* self) { _List_destroy((void*)self); } \
+ \
+static inline void List_##T##_push(List(T)* self, T value) { \
+    T* empty_cell = (T*)(_List_expand((void*)self, 1)); \
+    *empty_cell = value; \
+} \
+ \
+static inline void List_##T##_pushMany(List(T)* self, T* values_ptr, u32 len) { \
+    _List_push((void*)self, values_ptr, len); \
+} \
+ \
+/* alloc bigger buffer if size + len_to_add won't fit in current */ \
+static inline void List_##T##_increaseCapacity(List(T)* self, u32 len_to_add){ \
+    _List_increaseCapacity((void*)self, len_to_add); \
+} \
+ \
+static inline bool List_##T##_tryRemoveAt(List(T)* self, u32 i, u32 remove_len) ATTRIBUTE_WARN_UNUSED_RESULT; \
+static inline bool List_##T##_tryRemoveAt(List(T)* self, u32 i, u32 remove_len) { \
+    return _List_tryRemoveAt((void*)self, i, remove_len); \
+} \
+
+
 
 typedef struct List_ {
     void* data;
-    u32 size;
-    u32 allocated_size;
+    u32 len;
+    u32 capacity;
+    u32 elem_t_size;
 } List_;
 
-#define List_construct(T, DATA_PTR, OCCUPIED_COUNT, ALLOCATED_COUNT) \
-    List_construct_size(DATA_PTR, (OCCUPIED_COUNT) * sizeof(T), (ALLOCATED_COUNT) * sizeof(T))
-
-static inline List_ List_construct_size(void* data_ptr, u32 occupied_size, u32 allocated_size) {
-    return (List_){ .data = data_ptr, .size = occupied_size, .allocated_size = allocated_size };
+static inline List_ _List_construct(void* data_ptr, u32 len, u32 capacity, u32 elem_t_size) {
+    return (List_){
+        .data = data_ptr,
+        .len = len, 
+        .capacity = capacity,
+        .elem_t_size = elem_t_size
+    };
 }
-#define List_null List_construct_size(NULL, 0, 0)
 
-#define List_alloc(T, INITIAL_COUNT) List_alloc_size((INITIAL_COUNT) * sizeof(T))
-List_ List_alloc_size(u32 initial_size);
-
-static inline void List_destroy(List_* self){
+static inline void _List_destroy(List_* self){
     if(!self)
         return;
     free(self->data);
 }
 
-List_ List_copy(List_ src);
-
-// alloc bigger buffer if size + size_to_add won't fit in current
-void List_increaseCapacity_size(List_* self, u32 size_to_add);
-void* List_expand_size(List_* self, u32 size_to_add);
-#define List_push(SELF, T, VALUE) *(T*)(List_expand_size(SELF, sizeof(T))) = VALUE
-#define List_pushMany(SELF, T, VALUES_PTR, COUNT) List_push_size(SELF, VALUES_PTR, (COUNT) * sizeof(T))
-void List_push_size(List_* self, void* values, u32 size);
-
-#define List_removeAt(SELF, T, I, COUNT) List_removeAt_size(SELF, (I)*sizeof(T), (COUNT) * sizeof(T))
-bool List_removeAt_size(List_* self, u32 i, u32 remove_size);
-
-#define List_len(SELF, T) (SELF.size / sizeof(T))
-#define List_index(SELF, T, I) (((T*)SELF.data)[I])
-
-#define List_castTo_Array(SELF) Array_construct_size(SELF.data, SELF.size)
+List_ _List_alloc(u32 initial_capacity, u32 elem_t_size);
+List_ _List_copy(const List_* src);
+/* alloc bigger buffer if size + len_to_add won't fit in current */
+void _List_increaseCapacity(List_* self, u32 len_to_add);
+void* _List_expand(List_* self, u32 len_to_add);
+void _List_push(List_* self, void* values, u32 len);
+bool _List_tryRemoveAt(List_* self, u32 i, u32 remove_len) ATTRIBUTE_WARN_UNUSED_RESULT;
diff --git a/include/tlibc/collections/List_impl/List_char.h b/include/tlibc/collections/List_impl/List_char.h
new file mode 100644
index 0000000..a6781d4
--- /dev/null
+++ b/include/tlibc/collections/List_impl/List_char.h
@@ -0,0 +1,2 @@
+#pragma once
+List_declare(char);
diff --git a/include/tlibc/collections/List_impl/List_f32.h b/include/tlibc/collections/List_impl/List_f32.h
new file mode 100644
index 0000000..c20e0c5
--- /dev/null
+++ b/include/tlibc/collections/List_impl/List_f32.h
@@ -0,0 +1,2 @@
+#pragma once
+List_declare(f32);
diff --git a/include/tlibc/collections/List_impl/List_f64.h b/include/tlibc/collections/List_impl/List_f64.h
new file mode 100644
index 0000000..3e7ad67
--- /dev/null
+++ b/include/tlibc/collections/List_impl/List_f64.h
@@ -0,0 +1,2 @@
+#pragma once
+List_declare(f64);
diff --git a/include/tlibc/collections/List_impl/List_i16.h b/include/tlibc/collections/List_impl/List_i16.h
new file mode 100644
index 0000000..876cbd9
--- /dev/null
+++ b/include/tlibc/collections/List_impl/List_i16.h
@@ -0,0 +1,2 @@
+#pragma once
+List_declare(i16);
diff --git a/include/tlibc/collections/List_impl/List_i32.h b/include/tlibc/collections/List_impl/List_i32.h
new file mode 100644
index 0000000..2bedc6b
--- /dev/null
+++ b/include/tlibc/collections/List_impl/List_i32.h
@@ -0,0 +1,2 @@
+#pragma once
+List_declare(i32);
diff --git a/include/tlibc/collections/List_impl/List_i64.h b/include/tlibc/collections/List_impl/List_i64.h
new file mode 100644
index 0000000..b02ae75
--- /dev/null
+++ b/include/tlibc/collections/List_impl/List_i64.h
@@ -0,0 +1,2 @@
+#pragma once
+List_declare(i64);
diff --git a/include/tlibc/collections/List_impl/List_i8.h b/include/tlibc/collections/List_impl/List_i8.h
new file mode 100644
index 0000000..55531f5
--- /dev/null
+++ b/include/tlibc/collections/List_impl/List_i8.h
@@ -0,0 +1,2 @@
+#pragma once
+List_declare(i8);
diff --git a/include/tlibc/collections/List_impl/List_u16.h b/include/tlibc/collections/List_impl/List_u16.h
new file mode 100644
index 0000000..49d908b
--- /dev/null
+++ b/include/tlibc/collections/List_impl/List_u16.h
@@ -0,0 +1,2 @@
+#pragma once
+List_declare(u16);
diff --git a/include/tlibc/collections/List_impl/List_u32.h b/include/tlibc/collections/List_impl/List_u32.h
new file mode 100644
index 0000000..b524fac
--- /dev/null
+++ b/include/tlibc/collections/List_impl/List_u32.h
@@ -0,0 +1,2 @@
+#pragma once
+List_declare(u32);
diff --git a/include/tlibc/collections/List_impl/List_u64.h b/include/tlibc/collections/List_impl/List_u64.h
new file mode 100644
index 0000000..88afbac
--- /dev/null
+++ b/include/tlibc/collections/List_impl/List_u64.h
@@ -0,0 +1,2 @@
+#pragma once
+List_declare(u64);
diff --git a/include/tlibc/collections/List_impl/List_u8.h b/include/tlibc/collections/List_impl/List_u8.h
new file mode 100644
index 0000000..cf450d4
--- /dev/null
+++ b/include/tlibc/collections/List_impl/List_u8.h
@@ -0,0 +1,2 @@
+#pragma once
+List_declare(u8);
diff --git a/include/tlibc/errors.h b/include/tlibc/errors.h
index 8cb498c..64e0257 100755
--- a/include/tlibc/errors.h
+++ b/include/tlibc/errors.h
@@ -9,12 +9,15 @@ typedef struct ErrorCallPos {
     cstr file; 
     cstr func;
 } ErrorCallPos;
+
 #define ErrorCallPos_here() (ErrorCallPos){\
     .line = __LINE__,\
     .file = __FILE__,\
     .func = __func__\
 }
 
+List_declare(ErrorCallPos);
+
 typedef struct Error {
     str msg;
     bool is_msg_on_heap;
diff --git a/include/tlibc/filesystem.h b/include/tlibc/filesystem.h
index 47dea68..8447410 100644
--- a/include/tlibc/filesystem.h
+++ b/include/tlibc/filesystem.h
@@ -4,6 +4,7 @@
 #include "errors.h"
 #include "string/str.h"
 #include "collections/Array.h"
+#include "collections/Array_impl/Array_u8.h"
 
 #if !defined(TLIBC_FS_USE_WINDOWS_H)
     #if defined(_WIN64) || defined(_WIN32)
@@ -93,7 +94,7 @@ static inline Result(void) file_writeBytes(FILE* f, const void* src, u64 size){
 }
 
 static inline Result(void) file_writeBytesArray(FILE* f, Array(u8) src){
-    return file_writeStructs(f, src.data, src.size, 1);
+    return file_writeStructs(f, src.data, src.len, 1);
 }
 
 
@@ -112,10 +113,10 @@ static inline Result(u64) file_readBytes(FILE* f, void* dst, u64 max_count){
     return file_readStructs(f, dst, 1, max_count);
 }
 
-/// @param dst array where .size is the maximum number of bytes to read
+/// @param dst array where .len is the maximum number of bytes to read
 /// @return number of bytes that were read (<=max_count)
 static inline Result(u64) file_readBytesArray(FILE* f, Array(u8) dst){
-    return file_readStructs(f, dst.data, 1, dst.size);
+    return file_readStructs(f, dst.data, 1, dst.len);
 }
 
 
@@ -127,9 +128,9 @@ static inline Result(void) file_readBytesExactly(FILE* f, void* dst, u64 exact_c
     return file_readStructsExactly(f, dst, 1, exact_count);
 }
 
-/// @param dst array where .size is the exact number of bytes to read
+/// @param dst array where .len is the exact number of bytes to read
 static inline Result(void) file_readBytesArrayExactly(FILE* f, Array(u8) dst){
-    return file_readStructsExactly(f, dst.data, 1, dst.size);
+    return file_readStructsExactly(f, dst.data, 1, dst.len);
 }
 
 /// @brief allocates array of size equal `file_getSize()` and reads whole file
diff --git a/include/tlibc/string/StringBuilder.h b/include/tlibc/string/StringBuilder.h
index ee4e721..a96c2ac 100755
--- a/include/tlibc/string/StringBuilder.h
+++ b/include/tlibc/string/StringBuilder.h
@@ -1,7 +1,7 @@
 #pragma once
 
 #include "../collections/List.h"
-#include "../collections/Array.h"
+#include "../collections/List_impl/List_char.h"
 #include "str.h"
 
 typedef struct StringBuilder {
@@ -9,17 +9,17 @@ typedef struct StringBuilder {
 } StringBuilder;
 
 static inline StringBuilder StringBuilder_alloc(u32 initial_size) { 
-    return (StringBuilder){ .buffer = List_alloc_size(initial_size) }; 
+    return (StringBuilder){ .buffer = List_char_alloc(initial_size) }; 
 }
 void StringBuilder_destroy(StringBuilder* b);
 
 static inline StringBuilder StringBuilder_copy(const StringBuilder* b){
-    return (StringBuilder) { .buffer = List_copy(b->buffer) };
+    return (StringBuilder) { .buffer = List_char_copy(&b->buffer) };
 }
 
-// alloc bigger buffer if size + size_to_add won't fit in current
-static inline void StringBuilder_increaseCapacity(StringBuilder* b, u32 size_to_add){
-    List_increaseCapacity_size(&b->buffer, size_to_add);
+// alloc bigger buffer if size + len_to_add won't fit in current
+static inline void StringBuilder_increaseCapacity(StringBuilder* b, u32 len_to_add){
+    List_char_increaseCapacity(&b->buffer, len_to_add);
 }
 
 
diff --git a/include/tlibc/string/str.h b/include/tlibc/string/str.h
index ec8af8d..78562e9 100755
--- a/include/tlibc/string/str.h
+++ b/include/tlibc/string/str.h
@@ -4,10 +4,12 @@
 #include "char.h"
 #include "cstr.h"
 #include "../collections/Array.h"
+#include "../collections/Array_impl/Array_char.h"
+#include "../collections/Array_impl/Array_u8.h"
 
 typedef struct str {
     char* data;
-    u32 size; // size of data in bytes without \0
+    u32 len; // size of data in bytes without \0
     bool isZeroTerminated;
 } str;
 
@@ -16,7 +18,7 @@ typedef struct str {
 /// creates str from a string literal
 #define STR(LITERAL) str_construct(LITERAL, ARRAY_LEN(LITERAL) - 1, true)
 
-#define str_construct(DATA, LEN, ZERO_TERMINATED) ((str){ .data = DATA, .size = LEN, .isZeroTerminated = ZERO_TERMINATED })
+#define str_construct(DATA, LEN, ZERO_TERMINATED) ((str){ .data = DATA, .len = LEN, .isZeroTerminated = ZERO_TERMINATED })
 
 static inline str str_from_cstr(cstr s_ptr){
     return str_construct((void*)s_ptr, strlen(s_ptr), true);
@@ -26,12 +28,18 @@ static inline void str_free(str s){
     free(s.data);
 }
 
-static inline Array_ str_castTo_Array(str s) {
-    return Array_construct_size(s.data, s.size);
+static inline Array(char) str_castTo_Array_char(str s) {
+    return Array_char_construct(s.data, s.len);
+}
+static inline Array(u8) str_castTo_Array_u8(str s) {
+    return Array_u8_construct((void*)s.data, s.len);
 }
 
-static inline str Array_castTo_str(Array_ a, bool isZeroTerminated) {
-    return str_construct(a.data, a.size, isZeroTerminated);
+static inline str Array_char_castTo_str(Array(char) a, bool isZeroTerminated) {
+    return str_construct(a.data, a.len, isZeroTerminated);
+}
+static inline str Array_u8_castTo_str(Array(u8) a, bool isZeroTerminated) {
+    return str_construct((void*)a.data, a.len, isZeroTerminated);
 }
 
 static const str str_null = str_construct(NULL, 0, 0);
@@ -74,5 +82,5 @@ static inline str str_sliceBefore(str s, u32 n){
 
 ///@return s[n...]
 static inline str str_sliceAfter(str s, u32 n){
-    return str_construct(s.data + n, s.size - n, s.isZeroTerminated);
+    return str_construct(s.data + n, s.len - n, s.isZeroTerminated);
 }
diff --git a/src/collections/HashMap.c b/src/collections/HashMap.c
index b82e44d..7bb30a7 100755
--- a/src/collections/HashMap.c
+++ b/src/collections/HashMap.c
@@ -1,4 +1,6 @@
 #include "tlibc/collections/HashMap.h"
+#include "tlibc/collections/Array.h"
+#include "tlibc/collections/Array_impl/Array_u32.h"
 #include <assert.h>
 
 //TODO: sort bucket keys for binary search
@@ -9,9 +11,14 @@
 static const Array(u32) __HashMap_heights = ARRAY(u32, {
     0, 17, 31, 61, 127, 257, 521, 1021, 2053, 4099, 8191, 16381,
     32771, 65521, 131071, 262147, 524287, 1048583, 2097169, 4194319,
-    8388617, 16777213, 33554467, 67108859, 134217757, 268435493
+    8388617, 16777213, 33554467, 67108859, 134217757, 268435493,
+    536871001, 1073742037, 2147484061
 });
 
+void HashMapBucket_construct(HashMapBucket* self, u32 value_t_size){
+    self->key_hash_list = List_HashMapKeyHash_construct(NULL, 0, 0);
+    self->value_list = _List_construct(NULL, 0, 0, value_t_size);
+}
 
 void HashMap_construct_size(HashMap_* self, u32 value_t_size, Destructor_t NULLABLE(value_destructor)){
     self->value_t_size = value_t_size;
@@ -27,9 +34,9 @@ void HashMap_destroy(HashMap_* self){
 
     for(u32 i = 0; i < self->height; i++){
         HashMapBucket* bu = &self->table[i];
-        u32 len = List_len(bu->key_hash_list, HashMapKeyHash);
         
         // free key strings
+        u32 len = bu->key_hash_list.len;
         for(u32 j = 0; j < len; j++){
             HashMapKeyHash* kh = (HashMapKeyHash*)bu->key_hash_list.data + j;
             free(kh->key.data);
@@ -38,7 +45,7 @@ void HashMap_destroy(HashMap_* self){
         // destroy values
         if(self->value_destructor){
             u8* value_ptr = (u8*)bu->value_list.data;
-            u8* end = value_ptr + bu->value_list.size;
+            u8* end = value_ptr + bu->value_list.len * bu->value_list.elem_t_size;
             while(value_ptr < end){
                 self->value_destructor(value_ptr);
                 value_ptr += self->value_t_size;
@@ -68,7 +75,8 @@ static BucketAndIndex __HashMap_search(const HashMap_* self, const str key, u32
 
     BucketAndIndex r;
     r.bu = &self->table[hash % self->height];
-    for(r.i = 0; r.i < (i32)List_len(r.bu->key_hash_list, HashMapKeyHash); r.i++){
+    i32 len = r.bu->key_hash_list.len;
+    for(r.i = 0; r.i < len; r.i++){
         HashMapKeyHash* kh = (HashMapKeyHash*)r.bu->key_hash_list.data + r.i;
         if(kh->hash == hash && str_equals(kh->key, key)){
             return r;
@@ -91,29 +99,33 @@ void* HashMap_tryGetPtr(const HashMap_* self, const str key){
 
 static void __HashMap_expand(HashMap_* self){
     u32 height_expanded_n = self->height_n + 1;
-    assert(height_expanded_n < Array_len(__HashMap_heights, u32) && "HashMap IS FULL! Fix your code.");
+    assert(height_expanded_n < __HashMap_heights.len && "HashMap IS FULL! Fix your code.");
 
     // alloc new HashMapBucket array
-    u32 height_expanded = ((u32*)__HashMap_heights.data)[height_expanded_n];
+    u32 height_expanded = __HashMap_heights.data[height_expanded_n];
     u32 table_expanded_size = height_expanded * sizeof(HashMapBucket);
     HashMapBucket* table_expanded = (HashMapBucket*)malloc(table_expanded_size);
-    memset(table_expanded, 0, table_expanded_size);
+    // init buckets
+    for(u32 i = 0; i < height_expanded; i++){
+        HashMapBucket_construct(table_expanded + i, self->value_t_size);
+    }
 
     // copy values from old buckets to new
     for(u32 i = 0; i < self->height; i++){
         HashMapBucket* old_bucket = &self->table[i];
-        u32 len = List_len(old_bucket->key_hash_list, HashMapKeyHash);
         
+        u32 len = old_bucket->key_hash_list.len;
         for(u32 j = 0; j < len; j++){
-            HashMapKeyHash kh = ((HashMapKeyHash*)old_bucket->key_hash_list.data)[j];
-            HashMapBucket* new_bucket = &table_expanded[kh.hash % height_expanded];
-            List_push(&new_bucket->key_hash_list, HashMapKeyHash, kh);
+            HashMapKeyHash* kh = old_bucket->key_hash_list.data + j;
+            HashMapBucket* new_bucket = &table_expanded[kh->hash % height_expanded];
+            
+            List_HashMapKeyHash_pushMany(&new_bucket->key_hash_list, kh, 1);
             void* old_value_ptr = (u8*)old_bucket->value_list.data + j * self->value_t_size;
-            List_push_size(&new_bucket->value_list, old_value_ptr, self->value_t_size);
+            _List_push(&new_bucket->value_list, old_value_ptr, 1);
         }
         
-        free(old_bucket->key_hash_list.data);
-        free(old_bucket->value_list.data);
+        List_HashMapKeyHash_destroy(&old_bucket->key_hash_list);
+        _List_destroy(&old_bucket->value_list);
     }
     free(self->table);
     self->table = table_expanded;
@@ -129,14 +141,14 @@ bool HashMap_tryPush(HashMap_* self, const str key, void* value_ptr){
         return false;
 
     HashMapBucket* bu = r.bu;
-    if(bu == NULL || List_len(bu->key_hash_list, HashMapKeyHash) >= __HashMapBucket_MAX_LEN){
+    if(bu == NULL || r.bu->key_hash_list.len >= __HashMapBucket_MAX_LEN){
         __HashMap_expand(self);
         bu = &self->table[hash % self->height];
     }
     
     HashMapKeyHash kh = { .key = str_copy(key), .hash = hash };
-    List_push(&bu->key_hash_list, HashMapKeyHash, kh);
-    List_push_size(&bu->value_list, value_ptr, self->value_t_size);
+    List_HashMapKeyHash_push(&bu->key_hash_list, kh);
+    _List_push(&bu->value_list, value_ptr, 1);
     return true;
 }
 
@@ -151,14 +163,14 @@ void HashMap_pushOrUpdate(HashMap_* self, const str key, void* value_ptr){
     }
 
     HashMapBucket* bu = r.bu;
-    if(bu == NULL || List_len(bu->key_hash_list, HashMapKeyHash) >= __HashMapBucket_MAX_LEN){
+    if(bu == NULL || r.bu->key_hash_list.len >= __HashMapBucket_MAX_LEN){
         __HashMap_expand(self);
         bu = &self->table[hash % self->height];
     }
     
     HashMapKeyHash kh = { .key = str_copy(key), .hash = hash };
-    List_push(&bu->key_hash_list, HashMapKeyHash, kh);
-    List_push_size(&bu->value_list, value_ptr, self->value_t_size);
+    List_HashMapKeyHash_push(&bu->key_hash_list, kh);
+    _List_push(&bu->value_list, value_ptr, 1);
 }
 
 bool HashMap_tryDelete(HashMap_* self, const str key){
@@ -168,8 +180,11 @@ bool HashMap_tryDelete(HashMap_* self, const str key){
     if(r.i == -1)
         return false;
     
-    List_removeAt(&r.bu->key_hash_list, HashMapKeyHash, r.i, 1);
-    List_removeAt_size(&r.bu->value_list, r.i, self->value_t_size);
+    if(!List_HashMapKeyHash_tryRemoveAt(&r.bu->key_hash_list, r.i, 1))
+        return false;
+    if(!_List_tryRemoveAt(&r.bu->value_list, r.i, 1))
+        return false;
+    
     return true;
 }
 
@@ -182,7 +197,7 @@ bool HashMapIter_moveNext(HashMapIter* self){
     }
     // move to next element in current bucket
     const HashMapBucket* bu = &self->map->table[self->bucket_n];
-    i32 bu_elem_len = List_len(bu->key_hash_list, HashMapKeyHash);
+    i32 bu_elem_len = bu->key_hash_list.len;
     if(self->elem_n + 1 < bu_elem_len){
         self->elem_n++;
         return true;
@@ -193,7 +208,7 @@ bool HashMapIter_moveNext(HashMapIter* self){
             self->bucket_n++;
             self->elem_n = 0;
             bu = &self->map->table[self->bucket_n];
-            if(bu->key_hash_list.size != 0)
+            if(bu->key_hash_list.len != 0)
                 return true;
         }
     }
@@ -206,10 +221,10 @@ bool HashMapIter_getCurrent(HashMapIter* self, HashMapKeyValue* kv){
     
     const HashMapBucket* bu = &self->map->table[self->bucket_n];
     // table is empty
-    if(bu->key_hash_list.size == 0)
+    if(bu->key_hash_list.len == 0)
         return false;
     
-    kv->key = List_index(bu->key_hash_list, HashMapKeyHash, self->elem_n).key;
+    kv->key = bu->key_hash_list.data[self->elem_n].key;
     kv->value = (u8*)bu->value_list.data + self->map->value_t_size * self->elem_n;
     return true;
 }
diff --git a/src/collections/List.c b/src/collections/List.c
index d2fa4f2..9355981 100755
--- a/src/collections/List.c
+++ b/src/collections/List.c
@@ -1,55 +1,73 @@
 #include "tlibc/collections/List.h"
+#include <assert.h>
 
-List_ List_alloc_size(u32 initial_size){
-    if(initial_size == 0)
-        return List_null;
-    u32 allocated_size = ALIGN_TO(initial_size, sizeof(void*));
-    return List_construct_size(malloc(allocated_size), 0, allocated_size);
+List_ _List_alloc(u32 initial_capacity, u32 elem_t_size){
+    assert(elem_t_size != 0);
+    if(initial_capacity == 0)
+        return _List_construct(NULL, 0, 0, elem_t_size);
+    u32 initial_size = initial_capacity * elem_t_size;
+    u32 aligned_capacity = ALIGN_TO(initial_size, sizeof(void*));
+    return _List_construct(malloc(aligned_capacity), 0, aligned_capacity, elem_t_size);
 }
 
-List_ List_copy(const List_ src){
-    List_ copy = List_alloc_size(src.allocated_size);
-    if(copy.data != NULL)
-        memcpy(copy.data, src.data, src.size);
+List_ _List_copy(const List_* src){
+    assert(src->elem_t_size != 0);
+    List_ copy = _List_alloc(src->capacity, src->elem_t_size);
+    if(copy.data != NULL){
+        memcpy(copy.data, src->data, src->len * src->elem_t_size);
+    }
     return copy;
 }
 
-void List_increaseCapacity_size(List_* self, u32 size_to_add){
-    u32 occupied_size = self->size;
-    u32 expanded_size = occupied_size + size_to_add;
+void _List_increaseCapacity(List_* self, u32 len_to_add){
+    assert(self->elem_t_size != 0);
+
+    u32 expanded_len = self->len + len_to_add;
+    if(self->capacity > expanded_len) 
+        return;
     
-    if(self->allocated_size < expanded_size) {
-        u32 expanded_alloc_size = self->allocated_size;
-        if(expanded_alloc_size == 0)
-            expanded_alloc_size = 32;
-        while(expanded_alloc_size < expanded_size){
-            expanded_alloc_size *= 2;
-        }
-        // if self->data is null, realloc acts like malloc
-        self->data = realloc(self->data, expanded_alloc_size);
-        self->allocated_size = expanded_alloc_size;
+    u32 expanded_capacity = self->capacity;
+    if(expanded_capacity == 0)
+        expanded_capacity = 32;
+    while(expanded_capacity < expanded_len){
+        expanded_capacity *= 2;
     }
+    // if self->data is null, realloc acts like malloc
+    self->data = realloc(self->data, expanded_capacity * self->elem_t_size);
+    self->capacity = expanded_capacity;
 }
 
-void* List_expand_size(List_* self, u32 size_to_add){
-    List_increaseCapacity_size(self, size_to_add);
-    u8* empty_cell_ptr = (u8*)self->data + self->size;
-    self->size += size_to_add;
+void* _List_expand(List_* self, u32 len_to_add){
+    assert(self->elem_t_size != 0);
+    _List_increaseCapacity(self, len_to_add);
+    u8* empty_cell_ptr = (u8*)self->data + self->len * self->elem_t_size;
+    self->len += len_to_add;
     return empty_cell_ptr;
 }
 
-void List_push_size(List_* self, void* values, u32 size){
-    void* empty_cell_ptr = List_expand_size(self, size);
-    memcpy(empty_cell_ptr, values, size);
+void _List_push(List_* self, void* values, u32 len){
+    assert(self->elem_t_size != 0);
+    void* empty_cell_ptr = _List_expand(self, len);
+    memcpy(empty_cell_ptr, values, len * self->elem_t_size);
 }
 
-bool List_removeAt_size(List_* self, u32 i, u32 remove_size){
-    if(i + remove_size >= self->size)
+bool _List_tryRemoveAt(List_* self, u32 i, u32 remove_len){
+    assert(self->elem_t_size != 0);
+    
+    if(i >= self->len)
         return false;
     
-    self->size -= remove_size;
-    u8* src = (u8*)self->data + i + remove_size;
-    u8* dst = (u8*)self->data + i;
-    memmove(dst, src, self->size - i - remove_size);
+    if(remove_len + i > self->len)
+        remove_len = self->len - i;
+
+    u32 move_back_n_elements = self->len - i - remove_len;
+    if(move_back_n_elements > 0){
+        u32 move_back_size = move_back_n_elements * self->elem_t_size;
+        u8* dst = (u8*)self->data + i * self->elem_t_size;
+        u8* src = (u8*)self->data + (i + remove_len) * self->elem_t_size;
+        memmove(dst, src, move_back_size);
+    }
+    
+    self->len -= remove_len;
     return true;
 }
diff --git a/src/errors.c b/src/errors.c
index 8458a58..2ecbe22 100755
--- a/src/errors.c
+++ b/src/errors.c
@@ -11,7 +11,7 @@ Error* Error_create(const char* msg, bool is_msg_on_heap, ErrorCallPos p,
     e->is_msg_on_heap = is_msg_on_heap;
     e->error_code_page = error_code_page;
     e->error_code = error_code;
-    e->call_stack = List_alloc(ErrorCallPos, 16);
+    e->call_stack = List_ErrorCallPos_alloc(16);
     Error_addCallPos(e, p);
     return e;
 }
@@ -24,12 +24,12 @@ void Error_free(Error* e){
 }
 
 void Error_addCallPos(Error* e, ErrorCallPos p){
-    List_push(&e->call_stack, ErrorCallPos, p);
+    List_ErrorCallPos_push(&e->call_stack, p);
 }
 
 str Error_toStr(Error* e){
-    u32 len = List_len(e->call_stack, ErrorCallPos);
-    StringBuilder b = StringBuilder_alloc(e->msg.size + 80 * len);
+    u32 len = e->call_stack.len;
+    StringBuilder b = StringBuilder_alloc(e->msg.len + 80 * len);
     
     StringBuilder_append_str(&b, STR("Catched Error: "));
     StringBuilder_append_str(&b, e->msg);
@@ -50,7 +50,7 @@ str Error_toStr(Error* e){
 
 void Error_printAndExit(Error* e){
     str e_str = Error_toStr(e);
-    printfe("\n"FMT_str"\n", e_str.size, e_str.data);
+    printfe("\n"FMT_str"\n", e_str.len, e_str.data);
     free(e_str.data);
     Error_free(e);
     exit(111);
diff --git a/src/filesystem/file.c b/src/filesystem/file.c
index bc68cbf..f100b7a 100644
--- a/src/filesystem/file.c
+++ b/src/filesystem/file.c
@@ -141,7 +141,7 @@ Result(void) file_readWhole(FILE* f, Array(u8)* out_buf){
     bool success = false;
     
     try(i64 f_size, i, file_getSize(f));
-    Array(u8) buf = Array_alloc(u8, f_size);
+    Array(u8) buf = Array_u8_alloc(f_size);
     Defer(if(!success) free(buf.data));
     try_void(file_readBytesArray(f, buf));
 
diff --git a/src/filesystem/path.c b/src/filesystem/path.c
index ebd90f4..1ca48e2 100644
--- a/src/filesystem/path.c
+++ b/src/filesystem/path.c
@@ -1,36 +1,36 @@
 #include "tlibc/filesystem.h"
 
 str path_dirname(str path){
-    if(path.size == 0)
+    if(path.len == 0)
         return path;
 
     // remove trailing slash (name/)
-    if(path.data[path.size - 1] == path_sep){
-        path.size -= 1;
+    if(path.data[path.len - 1] == path_sep){
+        path.len -= 1;
     }
 
     i32 sepIndex = str_seekCharReverse(path, path_sep, -1);
     if(sepIndex < 0)
         return STR(".");
     
-    path.size = sepIndex;
+    path.len = sepIndex;
     path.isZeroTerminated = false;
     return path;
 }
 
 str path_basename(str path, bool remove_ext){
-    if(path.size == 0)
+    if(path.len == 0)
         return path;
     
     // remove trailing slash (name/)
-    if(path.data[path.size - 1] == path_sep){
-        path.size -= 1;
+    if(path.data[path.len - 1] == path_sep){
+        path.len -= 1;
     }
 
     i32 nameIndex = str_seekCharReverse(path, path_sep, -1) + 1;
     if((u32)nameIndex != 0){
         path.data += nameIndex;
-        path.size -= nameIndex;
+        path.len -= nameIndex;
     }
     
     if(!remove_ext)
@@ -38,7 +38,7 @@ str path_basename(str path, bool remove_ext){
     
     i32 extIndex = str_seekCharReverse(path, '.', -1);
     if(extIndex > 0){
-        path.size = extIndex;
+        path.len = extIndex;
         path.isZeroTerminated = false;
     }
     return path;
diff --git a/src/string/StringBuilder.c b/src/string/StringBuilder.c
index 84cc1ce..81c2b5c 100755
--- a/src/string/StringBuilder.c
+++ b/src/string/StringBuilder.c
@@ -8,41 +8,40 @@ void StringBuilder_destroy(StringBuilder* b){
 }
 
 str StringBuilder_getStr(StringBuilder* b){
-    if(b->buffer.size == 0 || ((char*)b->buffer.data)[b->buffer.size - 1] != '\0'){
-        List_push(&b->buffer, u8, '\0');
-        // '\0' at the end doesn't increase buffer.size
-        b->buffer.size -= 1;
+    if(b->buffer.len == 0 || b->buffer.data[b->buffer.len - 1] != '\0'){
+        List_char_push(&b->buffer, '\0');
+        // '\0' at the end doesn't increase buffer.len
+        b->buffer.len -= 1;
     }
-    str result = str_construct((char*)b->buffer.data, b->buffer.size, true);
+    str result = str_construct(b->buffer.data, b->buffer.len, true);
     return result;
 }
 
 bool StringBuilder_equals(const StringBuilder* a, const StringBuilder* b){
-    str a_str = str_construct((char*)a->buffer.data, a->buffer.size, false);
-    str b_str = str_construct((char*)b->buffer.data, b->buffer.size, false);
+    str a_str = str_construct(a->buffer.data, a->buffer.len, false);
+    str b_str = str_construct(b->buffer.data, b->buffer.len, false);
     return str_equals(a_str, b_str);
 }
 
 void StringBuilder_removeFromEnd(StringBuilder* b, u32 count){
-    if(count < b->buffer.size){
-        b->buffer.size -= count;
+    if(count < b->buffer.len){
+        b->buffer.len -= count;
     }
     else{
-        b->buffer.size = 0;
+        b->buffer.len = 0;
     }
 }
 
 
 void StringBuilder_append_char(StringBuilder* b, char c){
-    List_push(&b->buffer, u8, c);
+    List_char_push(&b->buffer, c);
 }
 
-
 void StringBuilder_append_str(StringBuilder* b, str s){
     if(s.data == NULL)
         return;
     
-    List_push_size(&b->buffer, s.data, s.size);
+    List_char_pushMany(&b->buffer, s.data, s.len);
 }
 
 void StringBuilder_append_cstr(StringBuilder* b, cstr s){
@@ -78,7 +77,7 @@ void StringBuilder_append_memory(StringBuilder* b, Array(u8) mem, bool uppercase
         return;
     
     char buf[8];
-    for (u32 i=0; i < mem.size; i++) {
+    for (u32 i=0; i < mem.len; i++) {
         sprintf(buf, uppercase ? "%02X" : "%02x", ((u8*)mem.data)[i]);
         StringBuilder_append_str(b, str_construct(buf, 2, true));
     }
diff --git a/src/string/str.c b/src/string/str.c
index e88aed0..3898491 100755
--- a/src/string/str.c
+++ b/src/string/str.c
@@ -2,17 +2,17 @@
 #include "tlibc/string/StringBuilder.h"
 
 str str_copy(const str self){
-    if(self.data == NULL || self.size == 0)
+    if(self.data == NULL || self.len == 0)
         return self;
     
-    str copy = str_construct((char*)malloc(self.size + 1), self.size, true);
-    memcpy(copy.data, self.data, self.size);
-    copy.data[copy.size] = '\0';
+    str copy = str_construct((char*)malloc(self.len + 1), self.len, true);
+    memcpy(copy.data, self.data, self.len);
+    copy.data[copy.len] = '\0';
     return copy;
 }
 
 bool str_equals(const str self, const str other){
-    if(self.size != other.size)
+    if(self.len != other.len)
         return false;
     if(self.data == other.data)
         return true;
@@ -23,26 +23,26 @@ bool str_equals(const str self, const str other){
         strncmp:        1.611s
         memcmp:         0.710s
     */
-    return memcmp(self.data, other.data, self.size) == 0;
+    return memcmp(self.data, other.data, self.len) == 0;
 }
 
 str str_reverse(str s){
-    if(s.data == NULL || s.size == 0)
+    if(s.data == NULL || s.len == 0)
         return s;
     
-    str r = str_construct(malloc(s.size), s.size, s.isZeroTerminated);
-    for(u32 i = 0; i < s.size; i++ )
-        r.data[i] = s.data[s.size - i - 1];
+    str r = str_construct(malloc(s.len), s.len, s.isZeroTerminated);
+    for(u32 i = 0; i < s.len; i++ )
+        r.data[i] = s.data[s.len - i - 1];
     return r;
 }
 
 i32 str_seek(const str src, const str fragment, u32 startIndex){
-    if(src.size == 0 || fragment.size == 0)
+    if(src.len == 0 || fragment.len == 0)
         return -1;
     
-    for(u32 i = startIndex; i < src.size - fragment.size + 1; i++){
+    for(u32 i = startIndex; i < src.len - fragment.len + 1; i++){
         for(u32 j = 0;; j++){
-            if(j == fragment.size)
+            if(j == fragment.len)
                 return i;
             if(src.data[i + j] != fragment.data[j])
                 break;
@@ -52,16 +52,16 @@ i32 str_seek(const str src, const str fragment, u32 startIndex){
 }
 
 i32 str_seekReverse(const str src, const str fragment, u32 startIndex){
-    if(src.size == 0 || fragment.size == 0)
+    if(src.len == 0 || fragment.len == 0)
         return -1;
     
-    if(startIndex > src.size - 1)
-        startIndex = src.size - 1;
-    for(u32 i = startIndex; i >= fragment.size - 1; i--){
+    if(startIndex > src.len - 1)
+        startIndex = src.len - 1;
+    for(u32 i = startIndex; i >= fragment.len - 1; i--){
         for(u32 j = 0;; j++){
-            if(j == fragment.size)
+            if(j == fragment.len)
                 return i - j + 1;
-            if(src.data[i - j] != fragment.data[fragment.size - 1 - j])
+            if(src.data[i - j] != fragment.data[fragment.len - 1 - j])
                 break;
         }
     }
@@ -69,7 +69,7 @@ i32 str_seekReverse(const str src, const str fragment, u32 startIndex){
 }
 
 i32 str_seekChar(const str src, char c, u32 startIndex){
-    for(u32 i = startIndex; i < src.size; i++){
+    for(u32 i = startIndex; i < src.len; i++){
         if(src.data[i] == c)
             return i;
     }
@@ -77,8 +77,8 @@ i32 str_seekChar(const str src, char c, u32 startIndex){
 }
 
 i32 str_seekCharReverse(const str src, char c, u32 startIndex){
-    if(startIndex > src.size - 1)
-        startIndex = src.size - 1;
+    if(startIndex > src.len - 1)
+        startIndex = src.len - 1;
     for(u32 i = startIndex; i != (u32)-1; i--){
         if(src.data[i] == c)
             return i;
@@ -87,36 +87,36 @@ i32 str_seekCharReverse(const str src, char c, u32 startIndex){
 }
 
 bool str_startsWith(const str src, const str fragment){
-    if(src.size < fragment.size)
+    if(src.len < fragment.len)
         return false;
     
     str src_fragment = str_null;
     src_fragment.data = src.data;
-    src_fragment.size = fragment.size;
+    src_fragment.len = fragment.len;
     return str_equals(src_fragment, fragment);
 }
 
 bool str_endsWith(const str src, const str fragment){
-    if(src.size < fragment.size)
+    if(src.len < fragment.len)
         return false;
     
     str src_fragment = str_null;
-    src_fragment.data = (char*)(src.data + src.size - fragment.size);
-    src_fragment.size = fragment.size;
+    src_fragment.data = (char*)(src.data + src.len - fragment.len);
+    src_fragment.len = fragment.len;
     return str_equals(src_fragment, fragment);
 }
 
 u32 str_hash32(const str s){
     u8* ubuf = (u8*)s.data;
     u32 hash=0;
-    for (u32 i = 0; i < s.size; i++)
+    for (u32 i = 0; i < s.len; i++)
         hash = (hash<<6) + (hash<<16) - hash + ubuf[i];
     return hash;
 }
 
 str str_toUpper(const str src){
     str r = str_copy(src);
-    for (u32 i = 0; i < r.size; i++){
+    for (u32 i = 0; i < r.len; i++){
         if(char_isLatinLower(r.data[i]))
             r.data[i] = r.data[i] - 'a' + 'A';
     }
@@ -125,7 +125,7 @@ str str_toUpper(const str src){
 
 str str_toLower(const str src){
     str r = str_copy(src);
-    for (u32 i = 0; i < r.size; i++){
+    for (u32 i = 0; i < r.len; i++){
         if(char_isLatinUpper(r.data[i]))
             r.data[i] = r.data[i] - 'A' + 'a';
     }
@@ -133,7 +133,7 @@ str str_toLower(const str src){
 }
 
 str hex_to_str(Array(u8) buf, bool uppercase){
-    StringBuilder sb = StringBuilder_alloc(buf.size * 2 + 1);
+    StringBuilder sb = StringBuilder_alloc(buf.len * 2 + 1);
     StringBuilder_append_memory(&sb, buf, uppercase);
     return StringBuilder_getStr(&sb);
 }
@@ -141,13 +141,13 @@ str hex_to_str(Array(u8) buf, bool uppercase){
 void str_trim(str* line, bool set_zero_at_end){
     // loop forward
     bool stop = false;
-    while(line->size > 0 && !stop){
+    while(line->len > 0 && !stop){
         char first_char = line->data[0];
         switch(first_char){
             case '\0': case '\r': case '\n':
             case '\t': case ' ':
                 line->data++;
-                line->size--;
+                line->len--;
                 break;
             default:
                 stop = true;
@@ -157,13 +157,13 @@ void str_trim(str* line, bool set_zero_at_end){
     
     // loop backward
     stop = false;
-    while(line->size > 0 && !stop)
+    while(line->len > 0 && !stop)
     {
-        char last_char = line->data[line->size - 1];
+        char last_char = line->data[line->len - 1];
         switch(last_char){
             case '\0': case '\r': case '\n':
             case '\t': case ' ':
-                line->size--;
+                line->len--;
                 break;
             default:
                 stop = true;
@@ -172,7 +172,7 @@ void str_trim(str* line, bool set_zero_at_end){
     }
 
     if(set_zero_at_end){
-        line->data[line->size] = '\0';
+        line->data[line->len] = '\0';
         line->isZeroTerminated = true;
     }
 }