fixed a bug in the `SpecialOptForce`

4 files changed, 13 insertions, 4 deletions

diff --git a/builtin.cpp b/builtin.cpp
index bbc2f93..1ab1d37 100644
--- a/builtin.cpp
+++ b/builtin.cpp
@@ -564,9 +564,10 @@ Pair *SpecialOptForce::call(Pair *_args, Environment * &lenvt,
     args = TO_PAIR(args->cdr);
     Pair *ret_addr = cont->pc;
     Pair *nexp = cont->state;
+    PromObj *prom = static_cast<PromObj*>(args->car);
     if (nexp)
     {
-        EvalObj *mem = args->car;
+        EvalObj *mem = TO_PAIR(args->cdr)->car;
         prom->feed_mem(mem);
         gc.expose(*top_ptr);
         *top_ptr++ = gc.attach(mem);
@@ -577,7 +578,6 @@ Pair *SpecialOptForce::call(Pair *_args, Environment * &lenvt,
     {
         if (!args->car->is_prom_obj())
             throw TokenError("a promise", RUN_ERR_WRONG_TYPE);
-        prom = static_cast<PromObj*>(args->car);
         EvalObj *mem = prom->get_mem();
         if (mem)                        // fetch from memorized result
         {
@@ -589,6 +589,7 @@ Pair *SpecialOptForce::call(Pair *_args, Environment * &lenvt,
         else                            // force
         {
             gc.attach(static_cast<EvalObj*>(*(++top_ptr)));
+            gc.attach(static_cast<EvalObj*>(*(++top_ptr)));
             top_ptr++;
             nexp = cont->state = prom->get_exp();
             nexp->next = NULL;
diff --git a/builtin.h b/builtin.h
index 67b07a7..b3053cd 100644
--- a/builtin.h
+++ b/builtin.h
@@ -163,8 +163,6 @@ class SpecialOptDelay: public SpecialOptObj {/*{{{*/
  * The implementation of `force` operator
  */
 class SpecialOptForce: public SpecialOptObj {/*{{{*/
-    private:
-        PromObj* prom;
     public:
         /** Construct a `force` operator */
         SpecialOptForce();
diff --git a/test/robust_test.log b/test/robust_test.log
index 6feaa56..7507f2a 100644
--- a/test/robust_test.log
+++ b/test/robust_test.log
@@ -202,3 +202,5 @@ Test Bibonacci numbers:
 218922995834555169026
 Test Eval: 
 92
+hello
+world
diff --git a/test/robust_test.scm b/test/robust_test.scm
index ed5dbfb..9e8c98d 100644
--- a/test/robust_test.scm
+++ b/test/robust_test.scm
@@ -393,3 +393,11 @@ x
 
 (display (queen 8))
 (display "\n")
+
+(define prom (delay (and (display "world\n") (lambda () 3))))
+(define prom2 (delay (and (display "hello\n") (force prom))))
+(force prom2)
+(force prom2)
+(force prom2)
+(force prom2)
+