bbc-basic/printer

   1 REM Printer library for mal in BBC BASIC
   2
   3 DEF FNpr_str(val%)
   4   LOCAL ret$
   5   IF FNis_int(val%) THEN =STR$(FNunbox_int(val%))
   6   IF FNis_symbol(val%) THEN =FNunbox_symbol(val%)
   7   IF FNis_list(val%) THEN
   8     ret$ = "("
   9     WHILE NOT FNis_empty(val%)
  10       IF LEN(ret$) > 1 THEN ret$ += " "
  11       ret$ += FNpr_str(FNlist_car(val%))
  12       val% = FNlist_cdr(val%)
  13     ENDWHILE
  14     =ret$ + ")"
  15   ENDIF
  16   ERROR 1, "Unprintable value"