xstdout now handles its own buffer. flush prompts before printing result expression.

include/picrin/cont.h

@@ -15,8 +15,8 @@ struct pic_cont {
 
   struct pic_block *blk;
 
-  size_t stk_len;
   pic_value *stk_pos, *stk_ptr;
+  size_t stk_len;
 
   pic_value *st_ptr;
   size_t sp_offset, st_len;

tools/main.c

@@ -136,9 +136,9 @@ repl(pic_state *pic)
       }
 
       /* print */
-      printf("=> ");
+      printf("=> "); fflush(stdout);
       pic_debug(pic, v);
-      printf("\n");
+      printf("\n"); fflush(stdout);
 
       vs = pic_cdr(pic, vs);
     }