diff --git a/.vscode/settings.json b/.vscode/settings.json
new file mode 100644
index 0000000..0ca8ea8
--- /dev/null
+++ b/.vscode/settings.json
@@ -0,0 +1,8 @@
+{
+  "files.associations": {
+    "*.lock": "yarnlock",
+    ".shards.info": "yaml",
+    ".graphqlconfig": "json",
+    "stdbool.h": "c"
+  }
+}
diff --git a/CMakeLists.txt b/CMakeLists.txt
index bc48ab4..7f3a5cc 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2,7 +2,17 @@ cmake_minimum_required(VERSION 3.22.1)
 
 project(hydroforth)
 
+include(CheckIPOSupported)
+check_ipo_supported(RESULT supported OUTPUT error)
+
 file(GLOB_RECURSE SOURCES ${PROJECT_SOURCE_DIR}/src/*.c)
 add_executable(hydroforth ${SOURCES})
 
+if( supported )
+    message(STATUS "IPO / LTO enabled")
+    set_property(TARGET hydroforth PROPERTY INTERPROCEDURAL_OPTIMIZATION TRUE)
+else()
+    message(STATUS "IPO / LTO not supported: <${error}>")
+endif()
+
 target_include_directories(hydroforth PRIVATE ${PROJECT_SOURCE_DIR}/include)
diff --git a/include/hydroforth/hydroforth.h b/include/hydroforth/hydroforth.h
index 6debd13..4f3edba 100644
--- a/include/hydroforth/hydroforth.h
+++ b/include/hydroforth/hydroforth.h
@@ -5,6 +5,8 @@
 
 #include "number.h"
 
+extern unsigned int hydroforth__hash_string(const char *const key, unsigned char length);
+
 typedef enum HYDROFORTH__WORD_TYPE
 {
   PUSH,
@@ -25,34 +27,69 @@ typedef struct HYDROFORTH__WORD
   HYDROFORTH__WORD_DATA data;
 } HYDROFORTH__WORD;
 
+typedef struct HYDROFORTH__WORD_DEFINITION
+{
+  HYDROFORTH__WORD *words;
+} HYDROFORTH__WORD_DEFINITION;
+
+typedef struct HYDROFORTH__WORD_DEFINITION_BASE_KEY
+{
+  unsigned char word_definition_index;
+} HYDROFORTH__WORD_DEFINITION_BASE_KEY;
+
+typedef struct HYDROFORTH__WORD_DEFINITION_SINGLE_CHAR_WORD_KEY
+{
+  char c;
+  HYDROFORTH__WORD_DEFINITION_BASE_KEY key;
+} HYDROFORTH__WORD_DEFINITION_SINGLE_CHAR_WORD_KEY;
+
+typedef struct HYDROFORTH__WORD_DEFINITION_WORD_KEY
+{
+  unsigned int hash;
+  HYDROFORTH__WORD_DEFINITION_BASE_KEY key;
+} HYDROFORTH__WORD_DEFINITION_WORD_KEY;
+
 typedef struct HYDROFORTH__INTERPRETER
 {
   char *src;
   unsigned long pos;
+  HYDROFORTH__WORD_DEFINITION_SINGLE_CHAR_WORD_KEY single_char_word_keys[32];
+  unsigned char single_char_word_keys_len;
+  unsigned short word_keys_len;
+  unsigned short word_keys_max_len;
+  HYDROFORTH__WORD_DEFINITION_WORD_KEY *word_keys;
+  HYDROFORTH__WORD_DEFINITION word_definitions[256];
   HYDROFORTH__WORD call_stack[256];
   unsigned char call_stack_len;
   int stack[256];
   unsigned char stack_len;
 } HYDROFORTH__INTERPRETER;
 
-extern bool hydroforth__step(HYDROFORTH__INTERPRETER *interpreter);
+extern bool hydroforth__parse(HYDROFORTH__INTERPRETER *interpreter);
+
+extern bool hydroforth__run_call_stack(HYDROFORTH__INTERPRETER *interpreter);
 
 extern bool hydroforth__run(HYDROFORTH__INTERPRETER *interpreter);
 
 typedef struct __HYDROFORTH
 {
   __HYDROFORTH__NUMBER number;
-  bool (*step)(HYDROFORTH__INTERPRETER *interpreter);
+  unsigned int (*hash_string)(const char *const key, unsigned char len);
+  bool (*parse)(HYDROFORTH__INTERPRETER *interpreter);
+  bool (*run_call_stack)(HYDROFORTH__INTERPRETER *interpreter);
   bool (*run)(HYDROFORTH__INTERPRETER *interpreter);
 } __HYDROFORTH;
 
 static const __HYDROFORTH hydroforth = {
     .number = {
         .is_digit = hydroforth__number__is_digit,
+        .convert_hex_digit = hydroforth__number__convert_hex_digit,
+        .parse_number_hex = hydroforth__number__parse_number_hex,
         .parse_number = hydroforth__number__parse_number,
-        .parse_number_with_sign = hydroforth__number__parse_number_with_sign,
     },
-    .step = hydroforth__step,
+    .hash_string = hydroforth__hash_string,
+    .parse = hydroforth__parse,
+    .run_call_stack = hydroforth__run_call_stack,
     .run = hydroforth__run,
 };
 
diff --git a/include/hydroforth/number.h b/include/hydroforth/number.h
index fab514a..bb92bbc 100644
--- a/include/hydroforth/number.h
+++ b/include/hydroforth/number.h
@@ -5,15 +5,18 @@
 
 extern bool hydroforth__number__is_digit(char c);
 
-extern bool hydroforth__number__parse_number(const char *const start, unsigned char len, int *const val);
+extern bool hydroforth__number__convert_hex_digit(char c, unsigned char *const val);
 
-extern bool hydroforth__number__parse_number_with_sign(const char *const start, unsigned char len, int *const val);
+extern bool hydroforth__number__parse_number_hex(const char *const start, unsigned char len, int *const val);
+
+extern bool hydroforth__number__parse_number(const char *const start, unsigned char len, int *const val);
 
 typedef struct __HYDROFORTH__NUMBER
 {
   bool (*is_digit)(char c);
+  bool (*convert_hex_digit)(char c, unsigned char *const val);
+  bool (*parse_number_hex)(const char *const start, unsigned char len, int *const val);
   bool (*parse_number)(const char *const start, unsigned char len, int *const val);
-  bool (*parse_number_with_sign)(const char *const start, unsigned char len, int *const val);
 } __HYDROFORTH__NUMBER;
 
 #endif
diff --git a/src/hydroforth/hydroforth.c b/src/hydroforth/hydroforth.c
index ba4d05c..c72d654 100644
--- a/src/hydroforth/hydroforth.c
+++ b/src/hydroforth/hydroforth.c
@@ -1,9 +1,28 @@
 #include <stdbool.h>
 #include <stdio.h>
+#include <malloc.h>
+#include <string.h>
 
 #include "hydroforth/hydroforth.h"
 
-bool hydroforth__step(HYDROFORTH__INTERPRETER *interpreter)
+unsigned int hydroforth__hash_string(const char *const key, unsigned char len)
+{
+  unsigned char i = 0;
+  unsigned int hash = 0;
+  while (i != len)
+  {
+    hash += key[i++];
+    hash += hash << 10;
+    hash ^= hash >> 6;
+  }
+  hash += hash << 3;
+  hash ^= hash >> 11;
+  hash += hash << 15;
+
+  return hash;
+}
+
+bool hydroforth__parse(HYDROFORTH__INTERPRETER *interpreter)
 {
   const unsigned long start = interpreter->pos;
   unsigned char len = 0;
@@ -12,7 +31,6 @@ bool hydroforth__step(HYDROFORTH__INTERPRETER *interpreter)
     len++;
     interpreter->pos++;
   }
-  printf("START: %lu\nLEN: %u\n", start, len);
   HYDROFORTH__WORD word;
   if (len == 1)
   {
@@ -33,22 +51,89 @@ bool hydroforth__step(HYDROFORTH__INTERPRETER *interpreter)
   }
   else
   {
-    if ((interpreter->src[start] == '-' || interpreter->src[start] == '+') &&
-        hydroforth__number__is_digit(interpreter->src[start + 1]))
+    const bool next_is_digit = hydroforth__number__is_digit(interpreter->src[start + 1]);
+    if (next_is_digit && interpreter->src[start] == '-')
     {
+      int n;
+      if (!hydroforth__number__parse_number(interpreter->src + start + 1, len - 1, &n))
+      {
+        fputs("Error parsing number!", stderr);
+        return false;
+      }
+      word = (HYDROFORTH__WORD){
+          .type = PUSH,
+          .data = {.number = -n},
+      };
+    }
+    else if (next_is_digit && interpreter->src[start] == '+')
+    {
+      int n;
+      if (!hydroforth__number__parse_number(interpreter->src + start + 1, len - 1, &n))
+      {
+        fputs("Error parsing number!", stderr);
+        return false;
+      }
+      word = (HYDROFORTH__WORD){
+          .type = PUSH,
+          .data = {.number = n},
+      };
     }
     else if (hydroforth__number__is_digit(interpreter->src[start]))
     {
       int n;
       if (!hydroforth__number__parse_number(interpreter->src + start, len, &n))
       {
-        printf("RESULT IS FALSE!!!\nNUMBER: %i\n", n);
+        fputs("Error parsing number!", stderr);
         return false;
       }
-      printf("NUMBER: %i\n", n);
+      word = (HYDROFORTH__WORD){
+          .type = PUSH,
+          .data = {.number = n},
+      };
     }
     else
     {
+      char *const s = malloc(sizeof(char) * (len + 1));
+      strncpy(s, interpreter->src + start, len);
+      s[len] = '\0';
+      word = (HYDROFORTH__WORD){
+          .type = WORD,
+          .data = {.word = s},
+      };
+    }
+  }
+
+  interpreter->call_stack[interpreter->call_stack_len++] = word;
+
+  return true;
+}
+
+bool hydroforth__run_call_stack(HYDROFORTH__INTERPRETER *interpreter)
+{
+  printf("CALL STACK LEN: %u\n", interpreter->call_stack_len);
+  for (unsigned char i = interpreter->call_stack_len; i > 0; interpreter->call_stack_len--, i--)
+  {
+    printf("TYPE: %u\n", interpreter->call_stack[i - 1].type);
+    const HYDROFORTH__WORD *word = interpreter->call_stack + i - 1;
+    switch (word->type)
+    {
+    case PUSH:
+      interpreter->stack[interpreter->stack_len++] = word->data.number;
+      break;
+
+    case CHAR_WORD:
+      switch (word->data.char_word)
+      {
+      case '-':
+        break;
+
+      default:
+        break;
+      }
+      break;
+
+    case WORD:
+      break;
     }
   }
 
@@ -65,10 +150,13 @@ bool hydroforth__run(HYDROFORTH__INTERPRETER *interpreter)
     }
     if (!interpreter->src[interpreter->pos])
     {
-      puts("END REACHED!");
       return true;
     }
-    if (!hydroforth__step(interpreter))
+    if (!hydroforth__parse(interpreter))
+    {
+      return false;
+    }
+    if (!hydroforth__run_call_stack(interpreter))
     {
       return false;
     }
diff --git a/src/hydroforth/number.c b/src/hydroforth/number.c
index 2b1cd42..18ae41d 100644
--- a/src/hydroforth/number.c
+++ b/src/hydroforth/number.c
@@ -8,9 +8,73 @@ bool hydroforth__number__is_digit(char c)
   return '0' <= c && c <= '9';
 }
 
+bool hydroforth__number__convert_hex_digit(char c, unsigned char *const val)
+{
+  if (hydroforth__number__is_digit(c))
+  {
+    *val = c - '0';
+  }
+  else
+  {
+    switch (c)
+    {
+    case 'A':
+    case 'a':
+      *val = 0xa;
+      break;
+
+    case 'B':
+    case 'b':
+      *val = 0xb;
+      break;
+
+    case 'C':
+    case 'c':
+      *val = 0xc;
+      break;
+
+    case 'D':
+    case 'd':
+      *val = 0xd;
+      break;
+
+    case 'E':
+    case 'e':
+      *val = 0xe;
+      break;
+
+    case 'F':
+    case 'f':
+      *val = 0xf;
+      break;
+
+    default:
+      return false;
+    }
+  }
+
+  return true;
+}
+
+bool hydroforth__number__parse_number_hex(const char *const start, unsigned char len, int *const val)
+{
+  int n;
+  for (unsigned char i = 0; i < len; i++)
+  {
+    unsigned char m;
+    if (!hydroforth__number__convert_hex_digit(start[i], &m))
+    {
+      return false;
+    }
+    n *= 16;
+    n += m;
+  }
+
+  return true;
+}
+
 bool hydroforth__number__parse_number(const char *const start, unsigned char len, int *const val)
 {
-  int num;
   if (start[0] == '0')
   {
     if (len > 1)
@@ -19,7 +83,7 @@ bool hydroforth__number__parse_number(const char *const start, unsigned char len
       {
       case 'X':
       case 'x':
-        return false;
+        return hydroforth__number__parse_number_hex(start + 2, len - 2, val);
 
       default:
         return hydroforth__number__parse_number(start + 1, len - 1, val);
@@ -43,7 +107,3 @@ bool hydroforth__number__parse_number(const char *const start, unsigned char len
     return true;
   }
 }
-
-bool hydroforth__number__parse_number_with_sign(const char *const start, unsigned char len, int *const val)
-{
-}
diff --git a/src/main.c b/src/main.c
index 3cffd1f..28cdb37 100644
--- a/src/main.c
+++ b/src/main.c
@@ -71,6 +71,9 @@ int main(int argc, char *argv[])
     HYDROFORTH__INTERPRETER interpreter = {
         .src = res.src,
         .pos = 0,
+        .single_char_word_keys_len = 0,
+        .word_keys_len = 0,
+        .word_keys_max_len = 0,
     };
     const bool run_res = hydroforth.run(&interpreter);
     free(res.src);