This will give you with-output-to-string function
gwmsh uses to get back results from gwm.

(with-output-to-string
  <form1>
  ...
  <formN>)

Forms are evaluated as in prog, but all output from calls to print
is directed to string returned as with-output-to-string value.

diff -c gwm-1.7o-dist/wool.c gwm-1.7o/wool.c
*** gwm-1.7o-dist/wool.c	Fri Sep 30 21:06:51 1994
--- gwm-1.7o/wool.c	Fri Sep 30 21:07:17 1994
***************
*** 1145,1150 ****
--- 1145,1186 ----
      return result;
  }
  
+ /*XXX-UWE-XXX*/
+ static int expand_string_stream ();
+ 
+ WOOL_OBJECT
+ wool_with_output_to_string (argc, argv)
+   int argc;
+   WOOL_OBJECT *argv;
+ {
+     WOOL_STRING_STREAM str, WOOL_STRING_STREAM_make (); 
+     int old_type;
+     char *old_stream;
+     WOOL_OBJECT result;
+ 
+     str = WOOL_STRING_STREAM_make (256, expand_string_stream);
+     old_type = wool_output_redirect (1, str, &old_stream);
+     progn (argc, argv);
+     wool_output_redirect (old_type, old_stream, NULL);
+ 
+     result = (WOOL_OBJECT) WLString_make (str->buffer);
+     WOOL_STRING_STREAM_free (str);
+     return result;
+ }
+ 
+ static int
+ expand_string_stream (str)
+   WOOL_STRING_STREAM str;
+ {
+     char *new_buf;
+     int nbytes = str->last - str->buffer + 1;
+     int ptr_pos = str->ptr - str->buffer;
+ 
+     str->buffer = Realloc (str->buffer, 2*nbytes);        
+     str->last = str->buffer + nbytes - 1;
+     str->ptr = str->buffer + ptr_pos;
+ }
+ /*XXX-UWE-XXX*/
  /*
   * (progn inst1 ... instn)
   * evals the n instructions then return the last one's result
***************
*** 1987,1992 ****
--- 2023,2032 ----
      wool_subr_make(WLSubr, shell, "!", NARY);
      increase_reference(wool_atom("print") -> c_val =
  		       wool_subr_make(WLSubr, wool_print_nary, "?", NARY));
+ /*XXX-UWE-XXX*/
+     wool_subr_make(WLFSubr, wool_with_output_to_string,
+                    "with-output-to-string", NARY);
+ /*XXX-UWE-XXX*/
      wool_subr_make(WLSubr, not, "not", 1);
      wool_subr_make(WLFSubr, and, "and", NARY);
      wool_subr_make(WLFSubr, or, "or", NARY);
diff -c gwm-1.7o-dist/wool.flex gwm-1.7o/wool.flex
*** gwm-1.7o-dist/wool.flex	Fri Sep 30 21:06:51 1994
--- gwm-1.7o/wool.flex	Fri Sep 30 21:07:17 1994
***************
*** 135,142 ****
  yyoutflush(){
      if(yyout_is_string){
          ASSERT(yystrout->overflow_handler);
! 	(*(yystrout->overflow_handler))(yystrout->buffer);
! 	yystrout->ptr = yystrout-> buffer;
      }else{
  	fflush(yyout);
      }
--- 135,144 ----
  yyoutflush(){
      if(yyout_is_string){
          ASSERT(yystrout->overflow_handler);
! /*XXX-UWE-XXX*/
! 	(*(yystrout->overflow_handler))(yystrout);
! 	/* yystrout->ptr = yystrout-> buffer; */
! /*XXX-UWE-XXX*/
      }else{
  	fflush(yyout);
      }
***************
*** 271,276 ****
--- 273,279 ----
      WOOL_STRING_STREAM str = (WOOL_STRING_STREAM)
      	Malloc(sizeof(struct _WOOL_STRING_STREAM));
      str->buffer = (char *) Malloc(nbytes);
+     *str->buffer = '\0';        /*XXX-UWE-XXX*/
      str->ptr = str->buffer;
      str->last = str->buffer + nbytes -1;
      str->overflow_handler = handler;