diff --git a/include/compiler/internals/gen.h b/include/compiler/internals/gen.h
index 369db48..59a117a 100644
--- a/include/compiler/internals/gen.h
+++ b/include/compiler/internals/gen.h
@@ -14,6 +14,7 @@
 #include <stdio.h>
 
 extern char *null_name;
+extern fzl_extern_type_t type_buf;
 
 bool gen_resolve_name(fzl_gen_t *gen, char *name, fzl_sym_t *sym);
 bool gen_resolve_type(fzl_gen_t *gen, fzl_token_t *tok, fzl_type_t *t, char *c);
diff --git a/src/compiler/fzl_walker.c b/src/compiler/fzl_walker.c
index 88b51fc..a998272 100644
--- a/src/compiler/fzl_walker.c
+++ b/src/compiler/fzl_walker.c
@@ -15,9 +15,6 @@
 #include <stdlib.h>
 #include <string.h>
 
-extern bool is_infinite_loop(fzl_walker_t *walker, fzl_node_t *node, size_t ls,
-                             size_t le);
-
 char *null_name = "<null>";
 char wlast_err[256];
 
@@ -234,7 +231,20 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
             .error = false, .type = FZL_TYPE_NULL, .classname = NULL};
         break;
 
-      case FZL_NODETYPE_EXTERN_FN: // TODO: write to meta
+      case FZL_NODETYPE_EXTERN_FN:
+      {
+        fzl_extern_fn_t *fn = &walker->extern_fns[walker->extern_fns_count++];
+        fn->has_return      = tok_to_type(node->ext_fn.type) != FZL_TYPE_NULL;
+
+        for (size_t i = 0; i < node->ext_fn.args_count; i++)
+        {
+          //
+        }
+
+        fn->args_count = node->ext_fn.args_count;
+        break;
+      }
+
       case FZL_NODETYPE_REFERENCE: // TODO: write to meta
       case FZL_NODETYPE_STRUCT:    // TODO: write to meta
       case FZL_NODETYPE_ALIAS:     // TODO: write to meta
diff --git a/src/compiler/generator/gen_alias.c b/src/compiler/generator/gen_alias.c
new file mode 100644
index 0000000..d2a2c1d
--- /dev/null
+++ b/src/compiler/generator/gen_alias.c
@@ -0,0 +1,30 @@
+#include <common/fzl_types.h>
+#include <compiler/internals/gen.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <string.h>
+
+// Type aliasing
+bool gen_alias(fzl_gen_t *gen, fzl_node_t *node)
+{
+  if (!gen || !node)
+    return false;
+
+  fzl_type_t type;
+  char typecn[256];
+  memset(typecn, 0, sizeof(typecn));
+
+  bool resolved = gen_resolve_type(gen, node->token, &type, typecn);
+  if (!resolved)
+    return false;
+
+  ssize_t slot = gen_resolve_extern_type(gen, typecn);
+  if (slot == -1)
+    type_buf.alias_target =
+        (fzl_extern_type_ref_t){.is_primitive = true, .primitive = type};
+  else
+    type_buf.alias_target =
+        (fzl_extern_type_ref_t){.is_primitive = false, .type_slot = slot};
+
+  return true;
+}
diff --git a/src/compiler/generator/gen_handle.c b/src/compiler/generator/gen_handle.c
new file mode 100644
index 0000000..c28b3e0
--- /dev/null
+++ b/src/compiler/generator/gen_handle.c
@@ -0,0 +1,13 @@
+#include <common/fzl_extern.h>
+#include <compiler/internals/gen.h>
+#include <stdbool.h>
+
+// Opaque pointer
+bool gen_handle(fzl_gen_t *gen, fzl_node_t *node)
+{
+  if (!gen || !node)
+    return false;
+
+  type_buf.kind = FZL_EXTERN_KIND_HANDLE;
+  return true;
+}
diff --git a/src/compiler/generator/gen_reference.c b/src/compiler/generator/gen_reference.c
new file mode 100644
index 0000000..8bf56be
--- /dev/null
+++ b/src/compiler/generator/gen_reference.c
@@ -0,0 +1,23 @@
+#include <common/fzl_extern.h>
+#include <compiler/fzl_token.h>
+#include <compiler/internals/gen.h>
+#include <stdbool.h>
+#include <stdio.h>
+
+// Type reference (convert T => T*)
+bool gen_reference(fzl_gen_t *gen, fzl_node_t *node)
+{
+  if (!gen || !node)
+    return false;
+
+  char *refname = (char *)node->token->value;
+  ssize_t slot  = gen_resolve_extern_type(gen, refname);
+  if (slot == -1)
+    return false;
+
+  type_buf.kind = FZL_EXTERN_KIND_REF;
+  type_buf.ref_target =
+      (fzl_extern_type_ref_t){.is_primitive = false, .type_slot = slot};
+
+  return true;
+}
diff --git a/src/compiler/generator/gen_struct.c b/src/compiler/generator/gen_struct.c
new file mode 100644
index 0000000..45bcc98
--- /dev/null
+++ b/src/compiler/generator/gen_struct.c
@@ -0,0 +1,102 @@
+#include <common/fzl_extern.h>
+#include <common/fzl_types.h>
+#include <compiler/fzl_gen.h>
+#include <compiler/fzl_parser.h>
+#include <compiler/internals/gen.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+// Structure
+bool gen_struct(fzl_gen_t *gen, fzl_node_t *node)
+{
+  if (!gen || !node)
+    return false;
+
+  type_buf.kind      = FZL_EXTERN_KIND_STRUCT;
+  fzl_gen_ctx_t *ctx = gen_ctx(gen, FZL_GEN_CTX_TYPE_UNECCESSARY, node);
+  if (!ctx)
+    return false;
+
+  size_t remainder = 2;
+  size_t count     = 0;
+  fzl_extern_struct_field_t *fields =
+      malloc(remainder * sizeof(fzl_extern_struct_field_t));
+  if (!fields)
+    return false;
+
+  for (size_t i = 0; i < node->structure.entries_count; i++)
+  {
+    fzl_node_t *fnode = node->structure.entries[i];
+    if (!gen_common(gen, fnode))
+    {
+      free(fields);
+      return false;
+    }
+
+    if (count >= remainder)
+    {
+      remainder *= 2;
+      fzl_extern_struct_field_t *newfields =
+          realloc(fields, remainder * sizeof(fzl_extern_struct_field_t));
+      if (!newfields)
+      {
+        free(fields);
+        return false;
+      }
+      fields = newfields;
+    }
+
+    fzl_type_t type;
+    char typecn[256];
+    memset(typecn, 0, sizeof(typecn));
+
+    fzl_extern_struct_field_t *field = &fields[count++];
+
+    if (node->type == FZL_NODETYPE_DECLARATION)
+    {
+      field->name = (char *)fnode->var.identifier->token->value;
+
+      bool resolved = gen_resolve_type(gen, fnode->var.type, &type, typecn);
+      if (!resolved)
+      {
+        free(fields);
+        return false;
+      }
+
+      ssize_t slot = gen_resolve_extern_type(gen, typecn);
+      if (slot == -1)
+        field->type =
+            (fzl_extern_type_ref_t){.is_primitive = true, .primitive = type};
+      else
+        field->type =
+            (fzl_extern_type_ref_t){.is_primitive = false, .type_slot = slot};
+    }
+    else if (node->type == FZL_NODETYPE_IDENTIFIER)
+    {
+      field->name = (char *)fnode->token->value;
+
+      ssize_t slot = gen_resolve_extern_type(gen, typecn);
+      if (slot == -1)
+      {
+        free(fields);
+        return false;
+      }
+      else
+        field->type =
+            (fzl_extern_type_ref_t){.is_primitive = false, .type_slot = slot};
+    }
+    else
+    {
+      free(fields);
+      return false;
+    }
+  }
+
+  type_buf.structure.fields       = fields;
+  type_buf.structure.fields_count = count;
+
+  return true;
+}
diff --git a/src/compiler/generator/gen_typedef.c b/src/compiler/generator/gen_typedef.c
new file mode 100644
index 0000000..bfe8eb9
--- /dev/null
+++ b/src/compiler/generator/gen_typedef.c
@@ -0,0 +1,45 @@
+#include <common/fzl_extern.h>
+#include <compiler/fzl_parser.h>
+#include <compiler/internals/gen.h>
+#include <stdbool.h>
+#include <string.h>
+
+fzl_extern_type_t type_buf;
+
+// Type definition
+bool gen_typedef(fzl_gen_t *gen, fzl_node_t *node)
+{
+  if (!gen || !node)
+    return false;
+
+  memset(&type_buf, 0, sizeof(type_buf));
+  if (!gen_common(gen, node->typedefinition.type))
+    return false;
+
+  fzl_extern_type_t *newtype = &gen->extern_types[gen->extern_types_count++];
+  newtype->lib_slot          = gen->extern_libs_count - 1;
+  newtype->name              = node->typedefinition.typename;
+
+  switch (type_buf.kind)
+  {
+    case FZL_EXTERN_KIND_REF:
+      newtype->kind       = FZL_EXTERN_KIND_REF;
+      newtype->ref_target = type_buf.ref_target;
+      break;
+
+    case FZL_EXTERN_KIND_HANDLE:
+      newtype->kind = FZL_EXTERN_KIND_HANDLE;
+      break;
+
+    case FZL_EXTERN_KIND_ALIAS:
+      newtype->alias_target = type_buf.alias_target;
+      break;
+
+    case FZL_EXTERN_KIND_STRUCT:
+      newtype->structure.fields       = type_buf.structure.fields;
+      newtype->structure.fields_count = type_buf.structure.fields_count;
+      break;
+  }
+
+  return true;
+}