diff --git a/Makefile b/Makefile
index 3aa63400..a10c3e0e 100644
--- a/Makefile
+++ b/Makefile
@@ -83,7 +83,8 @@ all: chibi-scheme$(EXE) libs
 COMPILED_LIBS := lib/srfi/27/rand$(SO) lib/srfi/33/bit$(SO) \
 	lib/srfi/69/hash$(SO) lib/srfi/98/env$(SO) \
 	lib/chibi/ast$(SO) lib/chibi/net$(SO) \
-	lib/chibi/posix$(SO) lib/chibi/heap-stats$(SO)
+	lib/chibi/filesystem$(SO) lib/chibi/process$(SO) \
+	lib/chibi/time$(SO) lib/chibi/heap-stats$(SO)
 
 libs: $(COMPILED_LIBS)
 
diff --git a/include/chibi/sexp.h b/include/chibi/sexp.h
index 30c542bd..73c78efb 100644
--- a/include/chibi/sexp.h
+++ b/include/chibi/sexp.h
@@ -696,6 +696,7 @@ enum sexp_context_globals {
   SEXP_G_OOM_ERROR,             /* out of memory exception object */
   SEXP_G_OOS_ERROR,             /* out of stack exception object */
   SEXP_G_OPTIMIZATIONS,
+  SEXP_G_SIGNAL_HANDLERS,
   SEXP_G_CONFIG_ENV,
   SEXP_G_MODULE_PATH,
   SEXP_G_QUOTE_SYMBOL,
diff --git a/lib/chibi/filesystem.module b/lib/chibi/filesystem.module
new file mode 100644
index 00000000..fe0fbdcf
--- /dev/null
+++ b/lib/chibi/filesystem.module
@@ -0,0 +1,22 @@
+
+(define-module (chibi filesystem)
+  (export open-input-file-descriptor open-output-file-descriptor
+          duplicate-file-descriptor duplicate-file-descriptor-to
+          close-file-descriptor renumber-file-descriptor
+          delete-file link-file symbolic-link-file rename-file
+          directory-files create-directory delete-directory
+          file-status
+          file-device               file-inode
+          file-mode                 file-num-links
+          file-owner                file-group
+          file-represented-device   file-size
+          file-block-size           file-num-blocks
+          file-access-time file-modification-time file-change-time
+          file-regular?    file-directory?        file-character?
+          file-block?      file-fifo?             file-link?
+          file-socket?
+          )
+  (import-immutable (scheme))
+  (include-shared "filesystem")
+  (include "filesystem.scm"))
+
diff --git a/lib/chibi/filesystem.scm b/lib/chibi/filesystem.scm
new file mode 100644
index 00000000..b3995221
--- /dev/null
+++ b/lib/chibi/filesystem.scm
@@ -0,0 +1,39 @@
+
+(define (directory-fold dir kons knil)
+  (let ((dir (opendir dir)))
+    (let lp ((res knil))
+      (let ((file (readdir dir)))
+        (if file (lp (kons (dirent-name file) res)) res)))))
+
+(define (directory-files dir)
+  (directory-fold dir cons '()))
+
+(define (renumber-file-descriptor old new)
+  (and (duplicate-file-descriptor-to old new)
+       (close-file-descriptor old)))
+
+(define (file-status file)
+  (if (string? file) (stat file) (fstat file)))
+
+(define (file-device x) (stat-dev (if (stat? x) x (file-status x))))
+(define (file-inode x) (stat-ino (if (stat? x) x (file-status x))))
+(define (file-mode x) (stat-mode (if (stat? x) x (file-status x))))
+(define (file-num-links x) (stat-nlinks (if (stat? x) x (file-status x))))
+(define (file-owner x) (stat-uid (if (stat? x) x (file-status x))))
+(define (file-group x) (stat-gid (if (stat? x) x (file-status x))))
+(define (file-represented-device x) (stat-rdev (if (stat? x) x (file-status x))))
+(define (file-size x) (stat-size (if (stat? x) x (file-status x))))
+(define (file-block-size x) (stat-blksize (if (stat? x) x (file-status x))))
+(define (file-num-blocks x) (stat-blocks (if (stat? x) x (file-status x))))
+(define (file-access-time x) (stat-atime (if (stat? x) x (file-status x))))
+(define (file-modification-time x) (stat-mtime (if (stat? x) x (file-status x))))
+(define (file-change-time x) (stat-ctime (if (stat? x) x (file-status x))))
+
+(define (file-regular? x) (S_ISREG (file-mode x)))
+(define (file-directory? x) (S_ISDIR (file-mode x)))
+(define (file-character? x) (S_ISCHR (file-mode x)))
+(define (file-block? x) (S_ISBLK (file-mode x)))
+(define (file-fifo? x) (S_ISFIFO (file-mode x)))
+(define (file-link? x) (S_ISLNK (file-mode x)))
+(define (file-socket? x) (S_ISSOCK (file-mode x)))
+
diff --git a/lib/chibi/filesystem.stub b/lib/chibi/filesystem.stub
new file mode 100644
index 00000000..ebd2f7be
--- /dev/null
+++ b/lib/chibi/filesystem.stub
@@ -0,0 +1,88 @@
+
+(c-system-include "sys/types.h")
+(c-system-include "unistd.h")
+(c-system-include "dirent.h")
+
+(define-c-struct DIR
+  finalizer: closedir)
+
+(define-c-struct dirent
+  (string d_name dirent-name))
+
+(define-c-struct stat
+  predicate: stat?
+  (dev_t      st_dev      stat-dev)
+  (ino_t      st_ino      stat-ino)
+  (mode_t     st_mode     stat-mode)
+  (nlink_t    st_nlink    stat-nlinks)
+  (uid_t      st_uid      stat-uid)
+  (gid_t      st_gid      stat-gid)
+  (dev_t      st_rdev     stat-rdev)
+  (off_t      st_size     stat-size)
+  (blksize_t  st_blksize  stat-blksize)
+  (blkcnt_t   st_blocks   stat-blocks)
+  (time_t     st_atime    stat-atime)
+  (time_t     st_mtime    stat-mtime)
+  (time_t     st_ctime    stat-ctime))
+
+(define-c boolean S_ISREG (mode_t))
+(define-c boolean S_ISDIR (mode_t))
+(define-c boolean S_ISCHR (mode_t))
+(define-c boolean S_ISBLK (mode_t))
+(define-c boolean S_ISFIFO (mode_t))
+(define-c boolean S_ISLNK (mode_t))
+(define-c boolean S_ISSOCK (mode_t))
+
+;;(define-c-const int ("S_IFMT"))
+(define-c-const int (file/socket "S_IFSOCK"))
+(define-c-const int (file/link "S_IFLNK"))
+(define-c-const int (file/regular "S_IFREG"))
+(define-c-const int (file/block "S_IFBLK"))
+(define-c-const int (file/directory "S_IFDIR"))
+(define-c-const int (file/character "S_IFCHR"))
+(define-c-const int (file/fifo "S_IFIFO"))
+(define-c-const int (file/suid "S_ISUID"))
+(define-c-const int (file/sgid "S_ISGID"))
+(define-c-const int (file/sticky "S_ISVTX"))
+;;(define-c-const int ("S_IRWXU"))
+(define-c-const int (perm/user-read "S_IRUSR"))
+(define-c-const int (perm/user-write "S_IWUSR"))
+(define-c-const int (perm/user-execute "S_IXUSR"))
+;;(define-c-const int ("S_IRWXG"))
+(define-c-const int (perm/group-read "S_IRGRP"))
+(define-c-const int (perm/group-write "S_IWGRP"))
+(define-c-const int (perm/group-execute "S_IXGRP"))
+;;(define-c-const int ("S_IRWXO"))
+(define-c-const int (perm/others-read "S_IROTH"))
+(define-c-const int (perm/others-write "S_IWOTH"))
+(define-c-const int (perm/others-execute "S_IXOTH"))
+
+(define-c errno stat (string (result stat)))
+(define-c errno fstat (int (result stat)))
+(define-c errno (file-link-status "lstat") (string (result stat)))
+
+(define-c input-port (open-input-file-descriptor "fdopen")
+  (int (value "r" string)))
+(define-c output-port (open-output-file-descriptor "fdopen")
+  (int (value "w" string)))
+
+(define-c errno (delete-file "unlink") (string))
+(define-c errno (link-file "link") (string string))
+(define-c errno (symbolic-link-file "symlink") (string string))
+(define-c errno (rename-file "rename") (string string))
+
+(define-c non-null-string (current-directory "getcwd")
+  ((result (array char (auto-expand arg1))) (value 256 int)))
+
+(define-c errno (create-directory "mkdir") (string int))
+(define-c errno (delete-directory "rmdir") (string))
+
+(define-c (free DIR) opendir (string))
+(define-c dirent readdir ((link DIR)))
+
+(define-c int (duplicate-file-descriptor "dup") (int))
+(define-c errno (duplicate-file-descriptor-to "dup2") (int int))
+(define-c errno (close-file-descriptor "close") (int))
+
+(define-c errno (open-pipe "pipe") ((result (array int 2))))
+(define-c errno (make-fifo "mkfifo") (string (default #o644 int)))
diff --git a/lib/chibi/posix.module b/lib/chibi/posix.module
deleted file mode 100644
index af726ff4..00000000
--- a/lib/chibi/posix.module
+++ /dev/null
@@ -1,12 +0,0 @@
-
-(define-module (chibi posix)
-  (export open-input-fd open-output-fd pipe
-          delete-file link-file symbolic-link-file rename-file
-          directory-files create-directory delete-directory
-          current-seconds
-          waitpid exit
-          )
-  (import-immutable (scheme))
-  (include-shared "posix")
-  (include "posix.scm"))
-
diff --git a/lib/chibi/posix.scm b/lib/chibi/posix.scm
deleted file mode 100644
index ed5fa780..00000000
--- a/lib/chibi/posix.scm
+++ /dev/null
@@ -1,10 +0,0 @@
-
-(define (directory-fold dir kons knil)
-  (let ((dir (opendir dir)))
-    (let lp ((res knil))
-      (let ((file (readdir dir)))
-        (if file (lp (kons (dirent-name file) res)) res)))))
-
-(define (directory-files dir)
-  (directory-fold dir cons '()))
-
diff --git a/lib/chibi/posix.stub b/lib/chibi/posix.stub
deleted file mode 100644
index 25dd5dbd..00000000
--- a/lib/chibi/posix.stub
+++ /dev/null
@@ -1,40 +0,0 @@
-
-(c-system-include "sys/types.h")
-(c-system-include "sys/wait.h")
-(c-system-include "time.h")
-(c-system-include "unistd.h")
-(c-system-include "dirent.h")
-
-(define-c-struct DIR
-  finalizer: closedir)
-
-(define-c-struct dirent
-  (string d_name dirent-name))
-
-(define-c input-port (open-input-fd "fdopen") (int (value "r" string)))
-(define-c output-port (open-output-fd "fdopen") (int (value "w" string)))
-
-(define-c errno (delete-file "unlink") (string))
-(define-c errno (link-file "link") (string string))
-(define-c errno (symbolic-link-file "symlink") (string string))
-(define-c errno (rename-file "rename") (string string))
-
-(define-c non-null-string (current-directory "getcwd")
-  ((result (array char (auto-expand arg1))) (value 256 int)))
-(define-c errno (create-directory "mkdir") (string int))
-(define-c errno (delete-directory "rmdir") (string))
-
-(define-c (free DIR) opendir (string))
-(define-c dirent readdir ((link DIR)))
-
-(define-c int (duplicate-fd "dup") (int))
-
-(define-c pid_t fork ())
-(define-c pid_t waitpid (int (result int) int))
-(define-c void exit (int))
-(define-c int (execute execvp) (string (array string)))
-
-(define-c errno pipe ((result (array int 2))))
-
-(define-c time_t (current-seconds "time") ((value NULL)))
-
diff --git a/lib/chibi/process.module b/lib/chibi/process.module
new file mode 100644
index 00000000..3e3f2cdb
--- /dev/null
+++ b/lib/chibi/process.module
@@ -0,0 +1,17 @@
+
+(define-module (chibi process)
+  (export exit sleep fork kill execute waitpid
+          set-signal-action! make-signal-set signal-set-contains?
+          signal-set-fill! signal-set-add! signal-set-delete!
+          current-signal-mask
+          signal-mask-block! signal-mask-unblock! signal-mask-set!
+          signal/hang-up    signal/interrupt   signal/quit
+          signal/illegal    signal/abort       signal/fpe
+          signal/kill       signal/segv        signal/pipe
+          signal/alarm      signal/term        signal/user1
+          signal/user2      signal/child       signal/continue
+          signal/stop       signal/tty-stop    signal/tty-input
+          signal/tty-output)
+  (import-immutable (scheme))
+  (include-shared "process"))
+
diff --git a/lib/chibi/process.stub b/lib/chibi/process.stub
new file mode 100644
index 00000000..baa5a7a5
--- /dev/null
+++ b/lib/chibi/process.stub
@@ -0,0 +1,69 @@
+
+(c-system-include "sys/types.h")
+(c-system-include "sys/wait.h")
+(c-system-include "signal.h")
+(c-system-include "unistd.h")
+
+(define-c-struct siginfo
+  predicate: signal-info?
+  (int      si_signo    signal-number)
+  (int      si_errno    signal-error-number)
+  (int      si_code     signal-code)
+  (pid_t    si_pid      signal-pid)
+  (uid_t    si_uid      signal-uid)
+  (int      si_status   signal-status)
+  (clock_t  si_utime    signal-user-time)
+  (clock_t  si_stime    signal-system-time))
+
+(define-c-type sigset_t
+  predicate: signal-set?)
+
+(define-c-const int (signal/hang-up "SIGHUP"))
+(define-c-const int (signal/interrupt "SIGINT"))
+(define-c-const int (signal/quit "SIGQUIT"))
+(define-c-const int (signal/illegal "SIGILL"))
+(define-c-const int (signal/abort "SIGABRT"))
+(define-c-const int (signal/fpe "SIGFPE"))
+(define-c-const int (signal/kill "SIGKILL"))
+(define-c-const int (signal/segv "SIGSEGV"))
+(define-c-const int (signal/pipe "SIGPIPE"))
+(define-c-const int (signal/alarm "SIGALRM"))
+(define-c-const int (signal/term "SIGTERM"))
+(define-c-const int (signal/user1"SIGUSR1"))
+(define-c-const int (signal/user2 "SIGUSR2"))
+(define-c-const int (signal/child "SIGCHLD"))
+(define-c-const int (signal/continue "SIGCONT"))
+(define-c-const int (signal/stop "SIGSTOP"))
+(define-c-const int (signal/tty-stop "SIGTSTP"))
+(define-c-const int (signal/tty-input "SIGTTIN"))
+(define-c-const int (signal/tty-output "SIGTTOU"))
+
+(c-include "signal.c")
+
+(define-c sexp (set-signal-action! "sexp_set_signal_action")
+  ((value ctx sexp) sexp  sexp))
+
+(define-c errno (make-signal-set "sigemptyset") ((result sigset_t)))
+(define-c errno (signal-set-fill! "sigfillset") (sigset_t))
+(define-c errno (signal-set-add! "sigaddset") (sigset_t int))
+(define-c errno (signal-set-delete! "sigaddset") (sigset_t int))
+(define-c boolean (signal-set-contains? "sigismember") (sigset_t int))
+
+(define-c errno (signal-mask-block! "sigprocmask")
+  ((value SIG_BLOCK int) sigset_t (value NULL sigset_t)))
+(define-c errno (signal-mask-unblock! "sigprocmask")
+  ((value SIG_UNBLOCK int) sigset_t (value NULL sigset_t)))
+(define-c errno (signal-mask-set! "sigprocmask")
+  ((value SIG_SETMASK int) sigset_t (value NULL sigset_t)))
+(define-c errno (current-signal-mask "sigprocmask")
+  ((value SIG_BLOCK int) (value NULL sigset_t) (result sigset_t)))
+
+(define-c pid_t fork ())
+;;(define-c pid_t wait ((result int)))
+(define-c pid_t waitpid (int (result int) int))
+(define-c errno kill (int int))
+;;(define-c errno raise (int))
+(define-c unsigned-int sleep (unsigned-int))
+(define-c void exit (int))
+(define-c int (execute execvp) (string (array string)))
+
diff --git a/lib/chibi/time.module b/lib/chibi/time.module
new file mode 100644
index 00000000..84f2b800
--- /dev/null
+++ b/lib/chibi/time.module
@@ -0,0 +1,11 @@
+
+(define-module (chibi time)
+  (export current-seconds get-time-of-day set-time-of-day!
+          seconds->time seconds->string time->seconds time->string
+          timeval-seconds timeval-microseconds
+          timezone-offset timezone-dst-time
+          time-second time-minute time-hour time-day time-month time-year
+          time-day-of-week time-day-of-year time-dst?)
+  (import-immutable (scheme))
+  (include-shared "time"))
+
diff --git a/lib/chibi/time.stub b/lib/chibi/time.stub
new file mode 100644
index 00000000..b2d444a8
--- /dev/null
+++ b/lib/chibi/time.stub
@@ -0,0 +1,45 @@
+
+(c-system-include "time.h")
+(c-system-include "sys/time.h")
+
+(define-c-struct tm
+  (int     tm_sec    time-second)
+  (int     tm_min    time-minute)
+  (int     tm_hour   time-hour)
+  (int     tm_mday   time-day)
+  (int     tm_mon    time-month)
+  (int     tm_year   time-year)
+  (int     tm_wday   time-day-of-week)
+  (int     tm_yday   time-day-of-year)
+  (int     tm_isdst  time-dst?))
+
+(define-c-struct timeval
+  predicate: timeval?
+  (time_t  tv_sec          timeval-seconds)
+  (int     tv_usec         timeval-microseconds))
+
+(define-c-struct timezone
+  predicate: timezone?
+  (int     tz_minuteswest  timezone-offset)
+  (int     tz_dsttime      timezone-dst-time))
+
+(define-c time_t (current-seconds "time") ((value NULL)))
+
+(define-c errno (get-time-of-day "gettimeofday")
+  ((result timeval) (result timezone)))
+
+(define-c errno (set-time-of-day! "settimeofday")
+  ((maybe-null timeval) (maybe-null default NULL timezone)))
+
+(define-c non-null-pointer (seconds->time "localtime_r")
+  ((pointer time_t) (result tm)))
+
+(define-c time_t (time->seconds "mktime")
+  (tm))
+
+(define-c non-null-string (seconds->string "ctime_r")
+  ((pointer time_t) (result (array char 64))))
+
+(define-c non-null-string (time->string "asctime_r")
+  (tm (result (array char 64))))
+
diff --git a/lib/srfi/1.module b/lib/srfi/1.module
index 8d341b6b..3d3da044 100644
--- a/lib/srfi/1.module
+++ b/lib/srfi/1.module
@@ -18,7 +18,7 @@
    lset<= lset= lset-adjoin lset-union lset-union! lset-intersection
    lset-intersection! lset-difference lset-difference! lset-xor lset-xor!
    lset-diff+intersection lset-diff+intersection!)
-  (import-immutable (scheme))
+  (import (scheme))
   (include "1/predicates.scm"
            "1/selectors.scm"
            "1/search.scm"
diff --git a/tools/genstubs.scm b/tools/genstubs.scm
index 9f33ef91..c679c30c 100755
--- a/tools/genstubs.scm
+++ b/tools/genstubs.scm
@@ -139,6 +139,7 @@
 
 (define *types* '())
 (define *funcs* '())
+(define *consts* '())
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; type objects
@@ -202,10 +203,12 @@
 ;; type predicates
 
 (define (signed-int-type? type)
-  (memq type '(signed-char short int long)))
+  (memq type '(signed-char short int long boolean)))
 
 (define (unsigned-int-type? type)
-  (memq type '(unsigned-char unsigned-short unsigned-int unsigned-long size_t pid_t)))
+  (memq type '(unsigned-char unsigned-short unsigned-int unsigned-long
+               size_t off_t time_t clock_t dev_t ino_t mode_t nlink_t
+               uid_t gid_t pid_t blksize_t blkcnt_t sigval_t)))
 
 (define (int-type? type)
   (or (signed-int-type? type) (unsigned-int-type? type)))
@@ -214,14 +217,23 @@
   (memq type '(float double long-double long-long-double)))
 
 (define (string-type? type)
-  (memq type '(char* string env-string non-null-string)))
+  (or (memq type '(char* string env-string non-null-string))
+      (and (vector? type)
+           (type-array type)
+           (not (type-pointer? type))
+           (eq? 'char (type-base type)))))
 
 (define (error-type? type)
-  (memq type '(errno non-null-string)))
+  (memq type '(errno non-null-string non-null-pointer)))
 
 (define (array-type? type)
   (and (type-array type) (not (eq? 'char (type-base type)))))
 
+(define (basic-type? type)
+  (let ((type (parse-type type)))
+    (and (not (type-array type))
+         (not (assq (type-base type) *types*)))))
+
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; function objects
 
@@ -250,7 +262,7 @@
           (cond
            ((type-result? type)
             (lp (cdr ls) (+ i 1) (cons type results) (cons type c-args) s-args))
-           ((type-value type)
+           ((and (type-value type) (not (type-default? type)))
             (lp (cdr ls) (+ i 1) results (cons type c-args) s-args))
            (else
             (lp (cdr ls) (+ i 1) results (cons type c-args) (cons type s-args)))
@@ -303,10 +315,8 @@
       (define (collect) (if (= i from) res (cons (substring str from i) res)))
       (cond
        ((>= i len) (string-concatenate-reverse (collect)))
-       ((eqv? c (string-ref str i))
-        (lp (+ i 1) (+ i 1) (cons r (collect))))
-       (else
-        (lp from (+ i 1) res))))))
+       ((eqv? c (string-ref str i)) (lp (+ i 1) (+ i 1) (cons r (collect))))
+       (else (lp from (+ i 1) res))))))
 
 (define (string-scan c str . o)
   (let ((limit (string-length str)))
@@ -349,9 +359,21 @@
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; naming
 
+(define (c-char? c)
+  (or (char-alphabetic? c) (char-numeric? c) (memv c '(#\_ #\- #\! #\?))))
+
+(define (c-escape str)
+  (let ((len (string-length str)))
+    (let lp ((from 0) (i 0) (res '()))
+      (define (collect) (if (= i from) res (cons (substring str from i) res)))
+      (cond
+       ((>= i len) (string-concatenate-reverse (collect)))
+       ((not (c-char? (string-ref str i))) (lp (+ i 1) (+ i 1) (cons "_" (cons (number->string (char->integer (string-ref str i)) 16) (collect)))))
+       (else (lp from (+ i 1) res))))))
+
 (define (mangle x)
   (string-replace
-   (string-replace (string-replace (x->string x) #\- "_") #\? "_p")
+   (string-replace (string-replace (c-escape (x->string x)) #\- "_") #\? "_p")
    #\! "_x"))
 
 (define (generate-stub-name sym)
@@ -367,20 +389,38 @@
   (apply cat args)
   (newline))
 
+(define (c-include header)
+  (cat "\n#include \"" header "\"\n"))
+
 (define (c-system-include header)
   (cat "\n#include <" header ">\n"))
 
+(define (parse-struct-like ls)
+  (map (lambda (x) (if (pair? x) (cons (parse-type (car x)) (cdr x)) x)) ls))
+
+(define-syntax define-struct-like
+  (er-macro-transformer
+   (lambda (expr rename compare)
+     (set! *types*
+           `((,(cadr expr)
+              ,@(parse-struct-like (cddr expr)))
+             ,@*types*))
+     `(cat "\nstatic sexp_uint_t " ,(type-id-name (cadr expr)) ";\n"))))
+
 (define-syntax define-c-struct
   (er-macro-transformer
    (lambda (expr rename compare)
-     (set! *types*
-           (cons (map (lambda (x)
-                        (if (pair? x)
-                            (cons (parse-type (car x)) (cdr x))
-                            x))
-                      (cdr expr))
-                 *types*))
-     `(cat "\nstatic sexp_uint_t " ,(type-id-name (cadr expr)) ";\n"))))
+     `(define-struct-like ,(cadr expr) type: struct ,@(cddr expr)))))
+
+(define-syntax define-c-class
+  (er-macro-transformer
+   (lambda (expr rename compare)
+     `(define-struct-like ,(cadr expr) type: class ,@(cddr expr)))))
+
+(define-syntax define-c-type
+  (er-macro-transformer
+   (lambda (expr rename compare)
+     `(define-struct-like ,(cadr expr) ,@(cddr expr)))))
 
 (define-syntax define-c
   (er-macro-transformer
@@ -388,6 +428,12 @@
      (set! *funcs* (cons (parse-func (cdr expr)) *funcs*))
      #f)))
 
+(define-syntax define-c-const
+  (er-macro-transformer
+   (lambda (expr rename compare)
+     (set! *consts*
+           (cons (cons (parse-type (cadr expr)) (cddr expr)) *consts*)))))
+
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; C code generation
 
@@ -398,6 +444,8 @@
       (cat "((" val "), SEXP_VOID)"))
      ((or (eq? base 'sexp) (error-type? base))
       (cat val))
+     ((eq? base 'boolean)
+      (cat "sexp_make_boolean(" val ")"))
      ((eq? base 'time_t)
       (cat "sexp_make_integer(ctx, sexp_shift_epoch(" val "))"))
      ((int-type? base)
@@ -422,7 +470,11 @@
          (ctype
           (cat "sexp_make_cpointer(ctx, "  (type-id-name base) ", "
                val ", " (or (and (pair? o) (car o)) "SEXP_FALSE") ", "
-               (if (type-free? type) 1 0) ")"))
+               (if (or (type-free? type)
+                       (and (type-result? type) (not (basic-type? type))))
+                   1
+                   0)
+               ")"))
          (else
           (error "unknown type" base))))))))
 
@@ -432,8 +484,10 @@
     (cond
      ((eq? base 'sexp)
       (cat val))
+     ((eq? base 'boolean)
+      (cat "sexp_truep(" val ")"))
      ((eq? base 'time_t)
-      (cat "sexp_uint_value(sexp_unshift_epoch(" val "))"))
+      (cat "sexp_unshift_epoch(sexp_uint_value(" val "))"))
      ((signed-int-type? base)
       (cat "sexp_sint_value(" val ")"))
      ((unsigned-int-type? base)
@@ -462,6 +516,7 @@
      ((float-type? base) "sexp_flonump")
      ((string-type? base) "sexp_stringp")
      ((eq? base 'char) "sexp_charp")
+     ((eq? base 'boolean) "sexp_booleanp")
      (else #f))))
 
 (define (type-name type)
@@ -469,6 +524,7 @@
    (cond
     ((int-type? base) "integer")
     ((float-type? base) "flonum")
+    ((eq? 'boolean base) "int")
     (else base))))
 
 (define (base-type-c-name base)
@@ -479,12 +535,15 @@
 (define (type-c-name type)
   (let* ((type (parse-type type))
          (base (type-base type))
-         (struct? (assq base *types*)))
+         (type-spec (assq base *types*))
+         (struct-type
+          (cond ((and type-spec (memq 'type: type-spec)) => cadr)
+                (else #f))))
     (string-append
      (if (type-const? type) "const " "")
-     (if struct? "struct " "")
+     (if struct-type (string-append (symbol->string struct-type) " ") "")
      (string-replace (base-type-c-name base) #\- " ")
-     (if struct? "*" "")
+     (if type-spec "*" "")
      (if (type-pointer? type) "*" ""))))
 
 (define (check-type arg type)
@@ -515,7 +574,7 @@
          (array (type-array type))
          (base-type (type-base type)))
     (cond
-     (array
+     ((and array (not (string-type? type)))
       (cond
        ((number? array)
         (cat "  if (!sexp_listp(ctx, " arg ")"
@@ -544,9 +603,11 @@
          "  if (! " (lambda () (check-type arg type)) ")\n"
          "    return sexp_type_exception(ctx, \"not "
          (definite-article (type-name type)) "\", " arg ");\n"))
+       ((eq? 'sexp base-type))
+       ((string-type? type)
+        (write-validator arg 'string))
        (else
-        (if (not (eq? 'sexp (type-base type)))
-            (display "WARNING: don't know how to validate: " (current-error-port)))
+        (display "WARNING: don't know how to validate: " (current-error-port))
         (write type (current-error-port))
         (newline (current-error-port))
         (write type)))))))
@@ -588,7 +649,9 @@
          (gc-vars (if preserve-res? (cons "res" gc-vars) gc-vars))
          (sexps (if preserve-res? '() '("res")))
          (num-gc-vars (length gc-vars))
-         (ints (if (or return-res? (eq? 'non-null-string (type-base ret-type)))
+         (ints (if (or return-res?
+                       (memq (type-base ret-type)
+                             '(non-null-string non-null-pointer)))
                    '()
                    '("err")))
          (ints (if (or (array-type? ret-type)
@@ -596,8 +659,9 @@
                        (any array-type? scheme-args))
                    (cons "i" ints)
                    ints)))
-    (if(eq? 'non-null-string (type-base ret-type))
-        (cat "  char *err;\n"))
+    (case (type-base ret-type)
+      ((non-null-string) (cat "  char *err;\n"))
+      ((non-null-pointer) (cat "  void *err;\n")))
     (cond
      ((pair? ints)
       (cat "  int " (car ints))
@@ -624,6 +688,13 @@
      (append (if (type-array ret-type) (list ret-type) '())
              results
              (remove type-result? (filter type-array scheme-args))))
+    (for-each
+     (lambda (arg)
+       (cond
+        ((and (type-pointer? arg) (basic-type? arg))
+         (cat "  " (type-c-name (type-base arg))
+              " tmp" (type-index arg) ";\n"))))
+     scheme-args)
     (cond
      ((pair? sexps)
       (cat "  sexp " (car sexps))
@@ -657,7 +728,7 @@
               ";\n"
               "  tmp" (type-index a) " = buf" (type-index a) ";\n"))))
      (cond
-      ((and (not (type-result? a)) (type-array a))
+      ((and (not (type-result? a)) (type-array a) (not (string-type? a)))
        (if (not (number? (type-array a)))
            (cat "  tmp" (type-index a)
                 " = (" (type-c-name (type-base a)) "*) malloc("
@@ -670,9 +741,45 @@
             ";\n"
             "  }\n")
        (if (not (number? (type-array a)))
-           (cat "  tmp" (type-index a) "[i] = NULL;\n")))))
+           (cat "  tmp" (type-index a) "[i] = NULL;\n")))
+      ((and (type-result? a) (not (basic-type? a))
+            (not (type-free? a)) (not (type-auto-expand? a))
+            (or (not (type-array a))
+                (not (integer? (get-array-length func a)))))
+       (cat "  tmp" (type-index a) " = malloc(sizeof(tmp" (type-index a)
+            "[0]));\n"))
+      ((and (type-pointer? a) (basic-type? a))
+       (cat "  tmp" (type-index a) " = "
+            (lambda ()
+              (scheme->c-converter
+               a
+               (string-append "arg" (type-index-string a))))
+            ";\n"))))
    (func-c-args func)))
 
+(define (write-actual-parameter func arg)
+  (cond
+   ((and (not (type-default? arg)) (type-value arg))
+    => (lambda (x)
+         (cond
+          ((any (lambda (y)
+                  (and (type-array y)
+                       (eq? x (get-array-length func y))))
+                (func-c-args func))
+           => (lambda (y) (cat "len" (type-index y))))
+          (else (write x)))))
+   ((or (type-result? arg) (type-array arg))
+    (cat (if (or (type-pointer? arg) (type-free? arg) (basic-type? arg))
+             "&"
+             "")
+         "tmp" (type-index arg)))
+   ((and (type-pointer? arg) (basic-type? arg))
+    (cat "&tmp" (type-index arg)))
+   (else
+    (scheme->c-converter
+     arg
+     (string-append "arg" (type-index-string arg))))))
+
 (define (write-call func)
   (let ((ret-type (func-ret-type func))
         (c-name (func-c-name func))
@@ -691,23 +798,7 @@
        (for-each
         (lambda (arg)
           (if (> (type-index arg) 0) (cat ", "))
-          (cond
-           ((or (type-result? arg) (type-array arg))
-            (cat (if (or (type-pointer? arg) (type-array arg)) "" "&")
-                 "tmp" (type-index arg)))
-           ((type-value arg)
-            => (lambda (x)
-                 (cond
-                  ((any (lambda (y)
-                          (and (type-array y)
-                               (eq? x (get-array-length func y))))
-                        (func-c-args func))
-                   => (lambda (y) (cat "len" (type-index y))))
-                  (else (write x)))))
-           (else
-            (scheme->c-converter
-             arg
-             (string-append "arg" (type-index-string arg))))))
+          (write-actual-parameter func arg))
         c-args)
        (cat ")"))
      (cond
@@ -762,7 +853,10 @@
         (results (func-results func)))
     (if error-res?
         (cat "  if ("
-             (if (eq? 'non-null-string (type-base (func-ret-type func))) "!" "")
+             (if (memq (type-base (func-ret-type func))
+                       '(non-null-string non-null-pointer))
+                 "!"
+                 "")
              "err) {\n"
              (cond
               ((any type-auto-expand? (func-c-args func))
@@ -847,10 +941,21 @@
        "}\n\n"))
 
 (define (write-func-binding func)
-  (cat "  sexp_define_foreign(ctx, env, "
-       (lambda () (write (symbol->string (func-scheme-name func))))
-       ", " (length (func-scheme-args func))  ", "
-       (func-stub-name func) ");\n"))
+  (let ((default (and (pair? (func-scheme-args func))
+                      (type-default? (car (reverse (func-scheme-args func))))
+                      (car (reverse (func-scheme-args func))))))
+    (cat (if default
+             "  sexp_define_foreign_opt(ctx, env, "
+             "  sexp_define_foreign(ctx, env, ")
+         (lambda () (write (symbol->string (func-scheme-name func))))
+         ", " (length (func-scheme-args func))  ", "
+         (func-stub-name func)
+         (if default ", " "")
+         (if default
+             (lambda ()
+               (c->scheme-converter default (type-value default)))
+             "")
+         ");\n")))
 
 (define (write-type type)
   (let ((name (car type))
@@ -975,6 +1080,13 @@
                        *funcs*)))))))
      type)))
 
+(define (write-const const)
+  (let ((scheme-name (if (pair? (cadr const)) (caadr const) (cadr const)))
+        (c-name (if (pair? (cadr const)) (cadadr const) (mangle (cadr const)))))
+    (cat "  name = sexp_intern(ctx, \"" scheme-name "\");\n"
+         "  sexp_env_define(ctx, env, name, tmp="
+         (lambda () (c->scheme-converter (car const) c-name)) ");\n")))
+
 (define (write-utilities)
   (define (input-env-string? x)
     (and (eq? 'env-string (type-base x)) (not (type-result? x))))
@@ -1001,6 +1113,7 @@
   (cat "sexp sexp_init_library (sexp ctx, sexp env) {\n"
        "  sexp_gc_var2(name, tmp);\n"
        "  sexp_gc_preserve2(ctx, name, tmp);\n")
+  (for-each write-const *consts*)
   (for-each write-type *types*)
   (for-each write-func-binding *funcs*)
   (cat "  sexp_gc_release2(ctx);\n"