diff --git a/libguile/eval.c b/libguile/eval.c
index cca70f44d..74574fd55 100644
--- a/libguile/eval.c
+++ b/libguile/eval.c
@@ -2642,6 +2642,10 @@ evapply:
 	RETURN (SCM_BOOL_T);
       case scm_tc7_asubr:
 	RETURN (SCM_SUBRF (proc) (SCM_UNDEFINED, SCM_UNDEFINED));
+      case scm_tc7_smob:
+	if (!SCM_SMOB_DESCRIPTOR (proc).apply)
+	  goto badfun;
+	RETURN (scm_smob_apply_0 (proc));
 #ifdef CCLO
       case scm_tc7_cclo:
 	t.arg1 = proc;
@@ -2790,6 +2794,10 @@ evapply:
 #else
 	  RETURN (SCM_SUBRF (proc) (scm_cons (t.arg1, SCM_EOL)));
 #endif
+	case scm_tc7_smob:
+	  if (!SCM_SMOB_DESCRIPTOR (proc).apply)
+	    goto badfun;
+	  RETURN (scm_smob_apply_1 (proc, t.arg1));
 #ifdef CCLO
 	case scm_tc7_cclo:
 	  arg2 = t.arg1;
@@ -2908,6 +2916,10 @@ evapply:
 	case scm_tc7_rpsubr:
 	case scm_tc7_asubr:
 	  RETURN (SCM_SUBRF (proc) (t.arg1, arg2));
+	case scm_tc7_smob:
+	  if (!SCM_SMOB_DESCRIPTOR (proc).apply)
+	    goto badfun;
+	  RETURN (scm_smob_apply_2 (proc, t.arg1, arg2));
 #ifdef CCLO
 	cclon:
 	case scm_tc7_cclo:
@@ -3052,6 +3064,11 @@ evapply:
 				  SCM_CDR (SCM_CDR (debug.info->a.args))))
       case scm_tc7_lsubr:
 	RETURN (SCM_SUBRF (proc) (debug.info->a.args))
+      case scm_tc7_smob:
+	if (!SCM_SMOB_DESCRIPTOR (proc).apply)
+	  goto badfun;
+	RETURN (scm_smob_apply_3 (proc, t.arg1, arg2,
+				  SCM_CDDR (debug.info->a.args)));
 #ifdef CCLO
       case scm_tc7_cclo:
 	goto cclon;
@@ -3111,6 +3128,11 @@ evapply:
 	RETURN (SCM_SUBRF (proc) (scm_cons2 (t.arg1,
 					     arg2,
 					     scm_eval_args (x, env, proc))));
+      case scm_tc7_smob:
+	if (!SCM_SMOB_DESCRIPTOR (proc).apply)
+	  goto badfun;
+	RETURN (scm_smob_apply_3 (proc, t.arg1, arg2,
+				  scm_eval_args (x, env, proc)));
 #ifdef CCLO
       case scm_tc7_cclo:
 	goto cclon;
@@ -3471,6 +3493,18 @@ tail:
 	  proc = arg1;
 	}
       RETURN (EVALCAR (proc, args));
+    case scm_tc7_smob:
+      if (!SCM_SMOB_DESCRIPTOR (proc).apply)
+	goto badproc;
+      if (SCM_NULLP (args))
+	RETURN (scm_smob_apply_0 (proc))
+      else if (SCM_NULLP (SCM_CDR (args)))
+	RETURN (scm_smob_apply_1 (proc, SCM_CAR (args)))
+      else if (SCM_NULLP (SCM_CDDR (args)))
+	RETURN (scm_smob_apply_2 (proc, SCM_CAR (args), SCM_CADR (args)))
+      else
+	RETURN (scm_smob_apply_3 (proc, SCM_CAR (args), SCM_CADR (args),
+				  SCM_CDDR (args)));
     case scm_tc7_contin:
       SCM_ASRTGO (SCM_NULLP (args), wrongnumargs);
       scm_call_continuation (proc, arg1);
diff --git a/libguile/procs.c b/libguile/procs.c
index 8e53508bd..456cd19f0 100644
--- a/libguile/procs.c
+++ b/libguile/procs.c
@@ -50,6 +50,7 @@
 #include "libguile/objects.h"
 #include "libguile/strings.h"
 #include "libguile/vectors.h"
+#include "libguile/smob.h"
 
 #include "libguile/validate.h"
 #include "libguile/procs.h"
@@ -198,6 +199,8 @@ SCM_DEFINE (scm_procedure_p, "procedure?", 1, 0, 0,
 #endif
       case scm_tc7_pws:
 	return SCM_BOOL_T;
+      case scm_tc7_smob:
+	return SCM_BOOL (SCM_SMOB_DESCRIPTOR (obj).apply);
       default:
 	return SCM_BOOL_F;
       }
diff --git a/libguile/smob.c b/libguile/smob.c
index 406c5370b..da76f5694 100644
--- a/libguile/smob.c
+++ b/libguile/smob.c
@@ -122,6 +122,160 @@ scm_smob_print (SCM exp, SCM port, scm_print_state *pstate)
   return 1;
 }
 
+/* {Apply}
+ */
+
+SCM
+scm_smob_apply_0 (SCM smob)
+{
+  int type = SCM_SMOB_DESCRIPTOR (smob).gsubr_type;
+  switch (type)
+    {
+    case SCM_GSUBR_MAKTYPE (0, 0, 0):
+      return SCM_SMOB_DESCRIPTOR (smob).apply ();
+    case SCM_GSUBR_MAKTYPE (0, 1, 0):
+      return SCM_SMOB_DESCRIPTOR (smob).apply (smob, SCM_UNDEFINED);
+    case SCM_GSUBR_MAKTYPE (0, 0, 1):
+      return SCM_SMOB_DESCRIPTOR (smob).apply (smob, SCM_EOL);
+    case SCM_GSUBR_MAKTYPE (0, 2, 0):
+      return SCM_SMOB_DESCRIPTOR (smob).apply (smob,
+					       SCM_UNDEFINED,
+					       SCM_UNDEFINED);
+    case SCM_GSUBR_MAKTYPE (0, 1, 1):
+      return SCM_SMOB_DESCRIPTOR (smob).apply (smob,
+					       SCM_UNDEFINED,
+					       SCM_EOL);
+    case SCM_GSUBR_MAKTYPE (0, 3, 0):
+      return SCM_SMOB_DESCRIPTOR (smob).apply (smob,
+					       SCM_UNDEFINED,
+					       SCM_UNDEFINED,
+					       SCM_UNDEFINED);
+    case SCM_GSUBR_MAKTYPE (0, 2, 1):
+      return SCM_SMOB_DESCRIPTOR (smob).apply (smob,
+					       SCM_UNDEFINED,
+					       SCM_UNDEFINED,
+					       SCM_EOL);
+    default:
+      if (SCM_GSUBR_REQ (type) > 0)
+	scm_wrong_num_args (smob);
+      scm_misc_error ("scm_smob_apply_0",
+		      "Unsupported smob application: ~S",
+		      SCM_LIST1 (smob));
+    }
+}
+
+SCM
+scm_smob_apply_1 (SCM smob, SCM a1)
+{
+  int type = SCM_SMOB_DESCRIPTOR (smob).gsubr_type;
+  switch (type)
+    {
+    case SCM_GSUBR_MAKTYPE (0, 0, 0):
+      scm_wrong_num_args (smob);
+    case SCM_GSUBR_MAKTYPE (1, 0, 0):
+    case SCM_GSUBR_MAKTYPE (0, 1, 0):
+      return SCM_SMOB_DESCRIPTOR (smob).apply (smob, a1);
+    case SCM_GSUBR_MAKTYPE (0, 0, 1):
+      return SCM_SMOB_DESCRIPTOR (smob).apply (smob, SCM_LIST1 (a1));
+    case SCM_GSUBR_MAKTYPE (1, 1, 0):
+    case SCM_GSUBR_MAKTYPE (0, 2, 0):
+      return SCM_SMOB_DESCRIPTOR (smob).apply (smob, a1, SCM_UNDEFINED);
+    case SCM_GSUBR_MAKTYPE (1, 0, 1):
+    case SCM_GSUBR_MAKTYPE (0, 1, 1):
+      return SCM_SMOB_DESCRIPTOR (smob).apply (smob, a1, SCM_EOL);
+    case SCM_GSUBR_MAKTYPE (1, 2, 0):
+    case SCM_GSUBR_MAKTYPE (0, 3, 0):
+      return SCM_SMOB_DESCRIPTOR (smob).apply (smob, a1,
+					       SCM_UNDEFINED,
+					       SCM_UNDEFINED);
+    case SCM_GSUBR_MAKTYPE (1, 1, 1):
+    case SCM_GSUBR_MAKTYPE (0, 2, 1):
+      return SCM_SMOB_DESCRIPTOR (smob).apply (smob, a1,
+					       SCM_UNDEFINED,
+					       SCM_EOL);
+    default:
+      if (SCM_GSUBR_REQ (type) > 1)
+	scm_wrong_num_args (smob);
+      scm_misc_error ("scm_smob_apply_1",
+		      "Unsupported smob application: ~S",
+		      SCM_LIST1 (smob));
+    }
+}
+
+SCM
+scm_smob_apply_2 (SCM smob, SCM a1, SCM a2)
+{
+  int type = SCM_SMOB_DESCRIPTOR (smob).gsubr_type;
+  switch (type)
+    {
+    case SCM_GSUBR_MAKTYPE (0, 0, 0):
+    case SCM_GSUBR_MAKTYPE (1, 0, 0):
+    case SCM_GSUBR_MAKTYPE (0, 1, 0):
+      scm_wrong_num_args (smob);
+    case SCM_GSUBR_MAKTYPE (0, 0, 1):
+      return SCM_SMOB_DESCRIPTOR (smob).apply (smob, SCM_LIST2 (a1, a2));
+    case SCM_GSUBR_MAKTYPE (2, 0, 0):
+    case SCM_GSUBR_MAKTYPE (1, 1, 0):
+    case SCM_GSUBR_MAKTYPE (0, 2, 0):
+      return SCM_SMOB_DESCRIPTOR (smob).apply (smob, a1, a2);
+    case SCM_GSUBR_MAKTYPE (1, 0, 1):
+    case SCM_GSUBR_MAKTYPE (0, 1, 1):
+      return SCM_SMOB_DESCRIPTOR (smob).apply (smob, a1, SCM_LIST1 (a2));
+    case SCM_GSUBR_MAKTYPE (2, 1, 0):
+    case SCM_GSUBR_MAKTYPE (1, 2, 0):
+    case SCM_GSUBR_MAKTYPE (0, 3, 0):
+      return SCM_SMOB_DESCRIPTOR (smob).apply (smob, a1, a2, SCM_UNDEFINED);
+    case SCM_GSUBR_MAKTYPE (2, 0, 1):
+    case SCM_GSUBR_MAKTYPE (1, 1, 1):
+    case SCM_GSUBR_MAKTYPE (0, 2, 1):
+      return SCM_SMOB_DESCRIPTOR (smob).apply (smob, a1, a2, SCM_EOL);
+    default:
+      if (SCM_GSUBR_REQ (type) > 2)
+	scm_wrong_num_args (smob);
+      scm_misc_error ("scm_smob_apply_2",
+		      "Unsupported smob application: ~S",
+		      SCM_LIST1 (smob));
+    }
+}
+
+SCM
+scm_smob_apply_3 (SCM smob, SCM a1, SCM a2, SCM rest)
+{
+  int type = SCM_SMOB_DESCRIPTOR (smob).gsubr_type;
+  switch (type)
+    {
+    case SCM_GSUBR_MAKTYPE (0, 0, 0):
+    case SCM_GSUBR_MAKTYPE (1, 0, 0):
+    case SCM_GSUBR_MAKTYPE (0, 1, 0):
+    case SCM_GSUBR_MAKTYPE (2, 0, 0):
+    case SCM_GSUBR_MAKTYPE (1, 1, 0):
+    case SCM_GSUBR_MAKTYPE (0, 2, 0):
+      scm_wrong_num_args (smob);
+    case SCM_GSUBR_MAKTYPE (0, 0, 1):
+      return SCM_SMOB_DESCRIPTOR (smob).apply (smob, scm_cons (a1, scm_cons (a2, rest)));
+    case SCM_GSUBR_MAKTYPE (1, 0, 1):
+    case SCM_GSUBR_MAKTYPE (0, 1, 1):
+      return SCM_SMOB_DESCRIPTOR (smob).apply (smob, a1, scm_cons (a2, rest));
+    case SCM_GSUBR_MAKTYPE (3, 0, 0):
+    case SCM_GSUBR_MAKTYPE (2, 1, 0):
+    case SCM_GSUBR_MAKTYPE (1, 2, 0):
+    case SCM_GSUBR_MAKTYPE (0, 3, 0):
+      if (!SCM_NULLP (SCM_CDR (rest)))
+	scm_wrong_num_args (smob);
+      return SCM_SMOB_DESCRIPTOR (smob).apply (smob, a1, a2, SCM_CAR (rest));
+    case SCM_GSUBR_MAKTYPE (2, 0, 1):
+    case SCM_GSUBR_MAKTYPE (1, 1, 1):
+    case SCM_GSUBR_MAKTYPE (0, 2, 1):
+      return SCM_SMOB_DESCRIPTOR (smob).apply (smob, a1, a2, rest);
+    default:
+      if (SCM_GSUBR_REQ (type) > 3)
+	scm_wrong_num_args (smob);
+      scm_misc_error ("scm_smob_apply_3",
+		      "Unsupported smob application: ~S",
+		      SCM_LIST1 (smob));
+    }
+}
+
 long 
 scm_make_smob_type (char *name, scm_sizet size)
 {
@@ -141,6 +295,8 @@ scm_make_smob_type (char *name, scm_sizet size)
       scm_smobs[scm_numsmob].free = (size == 0 ? scm_free0 : scm_smob_free);
       scm_smobs[scm_numsmob].print = scm_smob_print;
       scm_smobs[scm_numsmob].equalp = 0;
+      scm_smobs[scm_numsmob].apply = 0;
+      scm_smobs[scm_numsmob].gsubr_type = 0;
       scm_numsmob++;
     }
   SCM_ALLOW_INTS;
@@ -192,6 +348,13 @@ scm_set_smob_equalp (long tc, SCM (*equalp) (SCM, SCM))
   scm_smobs[SCM_TC2SMOBNUM (tc)].equalp = equalp;
 }
 
+void
+scm_set_smob_apply (long tc, SCM (*apply) (), int req, int opt, int rst)
+{
+  scm_smobs[SCM_TC2SMOBNUM (tc)].apply = apply;
+  scm_smobs[SCM_TC2SMOBNUM (tc)].gsubr_type = SCM_GSUBR_MAKTYPE (req, opt, rst);
+}
+
 void
 scm_set_smob_mfpe (long tc, 
 		   SCM (*mark) (SCM),
diff --git a/libguile/smob.h b/libguile/smob.h
index 87839de3b..b6de488b6 100644
--- a/libguile/smob.h
+++ b/libguile/smob.h
@@ -57,6 +57,8 @@ typedef struct scm_smob_descriptor
   scm_sizet (*free) (SCM);
   int (*print) (SCM exp, SCM port, scm_print_state *pstate);
   SCM (*equalp) (SCM, SCM);
+  SCM (*apply) ();
+  int gsubr_type;
 } scm_smob_descriptor;
 
 
@@ -112,6 +114,7 @@ do { \
 #define SCM_SMOBNAME(smobnum)		(scm_smobs[smobnum].name)
 #define SCM_SMOB_PREDICATE(tag, obj)	(SCM_NIMP (obj) \
 					 && SCM_TYP16 (obj) == (tag))
+#define SCM_SMOB_DESCRIPTOR(x)		(scm_smobs[SCM_SMOBNUM (x)])
 
 extern int scm_numsmob;
 extern scm_smob_descriptor *scm_smobs;
@@ -124,6 +127,10 @@ extern scm_sizet scm_free0 (SCM ptr);
 extern scm_sizet scm_smob_free (SCM obj);
 extern int scm_smob_print (SCM exp, SCM port, scm_print_state *pstate);
 
+extern SCM scm_smob_apply_0 (SCM smob);
+extern SCM scm_smob_apply_1 (SCM smob, SCM a1);
+extern SCM scm_smob_apply_2 (SCM smob, SCM a1, SCM a2);
+extern SCM scm_smob_apply_3 (SCM smob, SCM a1, SCM a2, SCM rest);
 
 /* The following set of functions is the standard way to create new
  * SMOB types.
@@ -141,6 +148,7 @@ extern void scm_set_smob_print (long tc, int (*print) (SCM,
 						       SCM,
 						       scm_print_state*));
 extern void scm_set_smob_equalp (long tc, SCM (*equalp) (SCM, SCM));
+extern void scm_set_smob_apply (long tc, SCM (*apply) (), int req, int opt, int rst);
 
 
 /* Functions for registering multiple handler functions simultaneously.