* eval.c: Allow the test form of a for loop to be omitted,

defaulting to a true test, allowing an infinite loop to
be expressed as (for () () () ...).

* txr.1: Documented.

1 files changed, 2 insertions, 1 deletions

diff --git a/eval.c b/eval.c
index bc126c72..ff1d846f 100644
--- a/eval.c
+++ b/eval.c
@@ -1010,7 +1010,8 @@ static val op_for(val form, val env)
 
   uw_block_begin (nil, result);
 
-  for (; eval(car(cond), new_env, form); eval_progn(incs, new_env, form))
+  for (; cond == nil || eval(car(cond), new_env, form);
+       eval_progn(incs, new_env, form))
     eval_progn(forms, new_env, form);
 
   result = eval_progn(rest(cond), new_env, form);