diff --git a/Makefile b/Makefile
index 9ae4fab..f25a7ae 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 CHICKEN_C = csc
 
-MODULES = sexc sex-macros sex-modules utils fmt-c
+MODULES = sexc sex-macros sex-modules sex-types utils fmt-c
 OBJ = $(MODULES:%=%.o)
 
 sexc: main.o $(OBJ)
diff --git a/Readme.org b/Readme.org
index d08d78e..93aa815 100644
--- a/Readme.org
+++ b/Readme.org
@@ -12,7 +12,7 @@ to export ~CHICKEN_INSTALL_REPOSITORY~ and ~CHICKEN_REPOSITORY_PATH~
 environment variables. Refer to the documentation for more info:
 https://wiki.call-cc.org/man/5/Extension%20tools#changing-the-repository-location
 
-~chicken-install fmt getopt-long brev-separate test tree srfi-1 srfi-13~
+~chicken-install fmt getopt-long brev-separate test tree srfi-1 srfi-13 srfi-69~
 
 ** Compilation
 ~make~
diff --git a/example/begin.sex b/example/begin.sex
new file mode 100644
index 0000000..00e4002
--- /dev/null
+++ b/example/begin.sex
@@ -0,0 +1,8 @@
+(pub fn void other-fn ()
+  (begin (while true (begin 1 2 3 4)))
+  (switch a
+          ((1) (begin
+                (var (const char *) str "121232132")
+                (puts "str")))
+          ((2) (puts "2"))
+          (default (puts "more"))))
diff --git a/example/fn-no-args.sex b/example/fn-no-args.sex
new file mode 100644
index 0000000..a271620
--- /dev/null
+++ b/example/fn-no-args.sex
@@ -0,0 +1 @@
+(pub fn void no-args-fn () ())
diff --git a/example/hello-world.sex b/example/hello-world.sex
index f5da6e2..871d6ea 100644
--- a/example/hello-world.sex
+++ b/example/hello-world.sex
@@ -1,8 +1,8 @@
 (include stdio.h)
 
 (pub fn int main ((int argc) (char **argv))
-  (puts "Hello from Sex!")
   (var (array char 512) name)
+  (puts "Hello from Sex!")
   (puts "What is your name?")
   (scanf "%s" (cast char* &name))
   (printf "Hello, %s!\n" name)
diff --git a/example/polymorphism.sex b/example/polymorphism.sex
new file mode 100644
index 0000000..727943a
--- /dev/null
+++ b/example/polymorphism.sex
@@ -0,0 +1,25 @@
+(include stdint.h)
+
+(struct vec2
+  ((uint32_t x)
+   (uint32_t y)))
+
+(trait gui
+  (fn void update ((float dt)))
+  (fn void render ())
+  (fn vec2 get-position ())
+  (fn void add-child ((gui *w))))
+
+(struct button
+  ((vector gui) children)
+  ((vec2 pos)))
+
+(impl gui button
+  (fn void update ((float dt))
+    ())
+  (fn void render ()
+    ())
+  (fn vec2 get-position ()
+    (return self->pos))
+  (fn void add-child ((gui *w))
+    (push self->children w)))
diff --git a/sex-mode.el b/sex-mode.el
index 8eb676e..591f38d 100644
--- a/sex-mode.el
+++ b/sex-mode.el
@@ -35,11 +35,13 @@ All commands in `lisp-mode-shared-map' are inherited by this map.")
                                  "define"
                                  "defmacro"
                                  "extern"
+                                 "impl"
                                  "import"
                                  "include"
                                  "fn"
                                  "pub"
                                  "struct"
+                                 "trait"
                                  "var"
                                  "union")
                                'word)
@@ -57,6 +59,7 @@ All commands in `lisp-mode-shared-map' are inherited by this map.")
                                  "for"
                                  "goto"
                                  "return"
+                                 "self"
                                  "switch"
                                  "var"
                                  "while")
@@ -81,6 +84,8 @@ All commands in `lisp-mode-shared-map' are inherited by this map.")
 (put 'defmacro 'lisp-indent-function 'defun)
 (put 'struct 'lisp-indent-function 'defun)
 (put 'union 'lisp-indent-function 'defun)
+(put 'trait 'lisp-indent-function 'defun)
+(put 'impl 'lisp-indent-function 'defun)
 (put 'var 'lisp-indent-function 0)
 (put 'import 'lisp-indent-function 1)
 
diff --git a/sex-types.scm b/sex-types.scm
new file mode 100644
index 0000000..6aaeadb
--- /dev/null
+++ b/sex-types.scm
@@ -0,0 +1,23 @@
+(declare
+  (unit sex-types)
+  (uses fmt-c))
+
+(import fmt
+        srfi-69)
+
+(define +all-types+ (make-hash-table))
+
+(define (normalize-type type)
+  )
+
+(define (add-pointer type)
+  (list 'pointer type))
+
+(define (add-const type)
+  (list 'const type))
+
+(define (get-types-from-arglist arglist)
+  (list))
+
+(define (to-c-type type)
+  (fmt #f (c-type type)))
diff --git a/sexc.scm b/sexc.scm
index 01a8f2c..aa353cf 100644
--- a/sexc.scm
+++ b/sexc.scm
@@ -180,24 +180,35 @@
      (eval (cons 'import (cdr form))) acc)
     ((import)
      (append (process-raw-forms
-
               (import-modules (cdr form)) (list))
              acc))
     (else
      (walk-sex-tree form acc))))
 
 (define (process-raw-forms raw-forms acc)
+  "First processing pass"
   (if (null? raw-forms)
       (reverse acc)
       (process-raw-forms (cdr raw-forms)
                          (process-form (car raw-forms) acc))))
 
+;;; Second pass
+
+(define (process-sex-forms forms)
+  "Second processing pass.
+
+In this pass we do form-rearranging manipulations, like docstring extraction."
+  forms)
+
+;;; Aux functions
+
 (define (read-forms acc)
   (let ((r (read)))
     (if (eof-object? r) (reverse acc)
         (read-forms (cons r acc)))))
 
 (define (emit-c forms)
+  "Final conversion to C"
   (for-each (lambda (form)
               (fmt #t (c-expr form) nl))
             forms))
@@ -338,7 +349,9 @@
                (if (eq? input 'stdin)
                    (read-forms (list))
                    (read-from-file input)))
-              (sex-forms (process-input input raw-forms)))
+              (sex-forms
+               (process-sex-forms
+                (process-input input raw-forms))))
          (if (or (get-arg args 'macro-expand #f)
                  (get-arg args 'preprocess #f))
              ;; Preprocess or macroexpand