(pre-define scm-first SCM_CAR
  scm-tail SCM_CDR scm-c-define-procedure-c-init (define scm-c-define-procedure-c-temp SCM))

(pre-define (scm-is-undefined a) (= SCM-UNDEFINED a))

(pre-define (scm-c-define-procedure-c name required optional rest c-function documentation)
  ;defines and registers a c routine as a scheme procedure with documentation.
  ;like scm-c-define-gsubr but also sets documentation.
  ;scm-c-define-procedure-c-init must have been called in scope
  (set scm-c-define-procedure-c-temp (scm-c-define-gsubr name required optional rest c-function))
  (scm-set-procedure-property! scm-c-define-procedure-c-temp
    (scm-from-locale-symbol "documentation") (scm-from-locale-string documentation)))

(define (scm-debug-log value) (b0 SCM)
  ;display value with scheme write and add a newline
  (scm-call-2 (scm-variable-ref (scm-c-lookup "write")) value (scm-current-output-port))
  (scm-newline (scm-current-output-port)))

(define (scm-c-bytevector-take size-octets a) (SCM size-t b8*)
  ;creates a new bytevector of size-octects that contains the given bytevector
  (define r SCM (scm-c-make-bytevector size-octets))
  (memcpy (SCM-BYTEVECTOR-CONTENTS r) a size-octets) (return r))

(pre-define (scm-c-list-each list e body)
  ;SCM SCM c-compound-expression ->
  ;iterate over scm-list in c
  (while (not (scm-is-null list)) (set e (scm-first list)) body (set list (scm-tail list))))