The value NIL is not of type STREAM.

[Norbert Paul]

1 I do:

  (defun my-princ (object &optional output-stream)
      (write object
             :stream output-stream
             :readably nil
             :escape nil))
  ==> MY-PRINC

  (my-princ '(hello World))

then signals a TYPE-ERROR
  The value NIL is not of type STREAM.
  (SB-PRETTY::MAKE-PRETTY-STREAM NIL)
seems that the stream designator NIL is passed
that function which expects a stream instead.

What I expect is

  (my-princ '(hello World))
  (HELLO WORLD)
  ==> (HELLO WORLD)

Just like when I do

  (write '(Hello World)
         :stream nil
         :readably nil
         :escape nil)

which indeed behaves as expected:
See also:
   CLHS 22.4 The Printer Dictionary
    -> Function WRITE, PRIN1, PRINT, PPRINT, PRINC

This problem only occurs when MY-PRINC-ing lists.
With numbers, however, there is another problem:

  (my-princ 12) ; will return a wrong value
  12
  ==> NIL

but the equivalent write expression correctly gives

  (write 12 :stream nil :readably nil :escape nil)
 12
  ==>12

2 $ sbcl --version
   SBCL 1.0.25.debian

3 $ uname -a
   Linux pc92-e03-3 2.6.32-trunk-686 #1 SMP Sun Jan 10 06:32:16 UTC 2010 i686 GNU/Linux

4 *FEATURES*
  ==> (:SB-FUTEX :SB-THREAD :ANSI-CL :COMMON-LISP :SBCL :SB-DOC :SB-TEST :SB-LDB
     :SB-PACKAGE-LOCKS :SB-UNICODE :SB-EVAL :SB-SOURCE-LOCATIONS
     :IEEE-FLOATING-POINT :X86 :UNIX :ELF :LINUX :LARGEFILE :GENCGC
     :STACK-GROWS-DOWNWARD-NOT-UPWARD :C-STACK-IS-CONTROL-STACK
     :COMPARE-AND-SWAP-VOPS :UNWIND-TO-FRAME-AND-CALL-VOP :RAW-INSTANCE-INIT-VOPS
     :STACK-ALLOCATABLE-CLOSURES :ALIEN-CALLBACKS :CYCLE-COUNTER :LINKAGE-TABLE
     :OS-PROVIDES-DLOPEN :OS-PROVIDES-PUTWC :OS-PROVIDES-SUSECONDS-T)

[Stas Boukarev (stassats)]

That's another problem with WRITE compiler macro (https://bugs.launchpad.net/sbcl/+bug/581564)
 I attached a patch which combines fixing the above mentioned ticket and this issue. And it fixes another issue, compiler-macro returns NIL, while it should return an object.

[Stas Boukarev (stassats)]

I updated the patch for the current SBCL.

[Nikodemus Siivola (nikodemus)]

Thank you.

Committed in 1.0.42.4.