ABCL 1.2.1 doesn't seem to work

[pnathan]

Using latest version in Quicklisp:

CL-USER> (paiprolog:<- (edge v1 v2))
EDGE
CL-USER> (paiprolog:<- (edge v0 v2))
EDGE
CL-USER> (paiprolog:<- (edge v0 v3))
EDGE
CL-USER> (paiprolog:?- (edge ?vertex1 ?vertex2))
No.
; No value
CL-USER> 

I've tested this on SBCL and it works there. Not sure if there is compiler-specific code in the codebase; if not, I'll go take it over to the ABCL mailing list.

[kg6y-ucd]

I don't know why, but on ABCL bound-p returns T for unbound variable created by (?). If you re-evaluate the definition of bound-p in REPL, this (bound-p's) problem disappears.

PAIPROLOG> (lisp-implementation-version)
"1.3.1"
"Java_HotSpot(TM)_Client_VM-Oracle_Corporation-1.8.0_20-b26"
"x86-Windows_XP-5.1"
PAIPROLOG> (<- (p 1))
P
PAIPROLOG> (?- (p ?x))
No.
; No value
PAIPROLOG> (bound-p (?))
T
PAIPROLOG> (defun bound-p (var) (not (eq (var-binding var) unbound))) ;; from prologc.lisp
STYLE-WARNING: redefining BOUND-P at top level
BOUND-P
PAIPROLOG> (bound-p (?))
NIL
PAIPROLOG> (?- (p ?x))
?X = 1;

No.
; No value
PAIPROLOG> 

[kg6y-ucd]

When you embed debugging code in bound-p, problem becomes apparent .

;;; prologcp.lisp
(defun bound-p (var)
  (print-unreadable-object ((var-binding var) t :identity t :type t))
  (terpri)
  (print-unreadable-object (unbound t :identity t :type t))
  (not (eq (var-binding var) unbound)))

PAIPROLOG> (bound-p (?))
#<(SIMPLE-BASE-STRING 7) {165B2C7}>
#<(SIMPLE-BASE-STRING 7) {184CA5F}>
T
PAIPROLOG> 

[kg6y-ucd]

Changing (defconstant unbound ...) to (defvar unbound ...) in prologc.lisp might be a workaround for this problem. This is a simplified test case to show this workaround.

;;; test-bound-p.lisp

#-ABCL
(defconstant unbound "Unbound")
#+ABCL
(defvar unbound "Unbound") ;; workaround for ABCL

(defstruct var 
  (binding unbound))

(defun bound-p (var)
  (print-unreadable-object ((var-binding var) t :identity t :type t))
  (terpri)
  (print-unreadable-object (unbound t :identity t :type t))
  (not (eq (var-binding var) unbound)))

(defun run ()
  (print (bound-p (make-var))))

CL-USER> (compile-file "./test-bound-p.lisp")
; Compiling C:/lispbox-0.7/quicklisp/local-projects/paiprolog/test-bound-p.lisp ...
; (DEFVAR UNBOUND ...)
; (DEFSTRUCT VAR ...)
; (DEFUN BOUND-P ...)
; (DEFUN RUN ...)
; Wrote c:/lispbox-0.7/quicklisp/local-projects/paiprolog/./test-bound-p.abcl (0.701 seconds)
#P"C:/lispbox-0.7/quicklisp/local-projects/paiprolog/test-bound-p.abcl"
NIL
NIL
CL-USER> (run)
; Evaluation aborted on #<UNDEFINED-FUNCTION {6BE0B7}>.
CL-USER> (load "./test-bound-p.abcl")
T
CL-USER> (run)
#<(SIMPLE-BASE-STRING 7) {1596BBE}>
#<(SIMPLE-BASE-STRING 7) {1596BBE}>
NIL 
NIL
CL-USER> (lisp-implementation-version)
"1.3.3"
"Java_HotSpot(TM)_Client_VM-Oracle_Corporation-1.8.0_20-b26"
"x86-Windows_XP-5.1"
CL-USER> 

[quek]

https://github.com/quek/paiprolog/pull/10 Dose this fix the problem?

[kg6y-ucd]

No it doesn't. The patch below works for me.

uchita-akiko-no-macbook-2:paiprolog uchidamasako$ git diff
diff --git a/prologc.lisp b/prologc.lisp
index d44b203..2e667b3 100644
--- a/prologc.lisp
+++ b/prologc.lisp
@@ -7,11 +7,16 @@

 (in-package "PAIPROLOG")

-
+#-ABCL
 (defconstant unbound (if (boundp 'unbound)
                         (symbol-value 'unbound)
                         "Unbound"))

+#+ABCL
+(defvar unbound (if (boundp 'unbound)
+                    (symbol-value 'unbound)
+                    "Unbound"))
+
 (defvar *var-counter* 0)

 (defstruct (var (:constructor ? ())
uchita-akiko-no-macbook-2:paiprolog uchidamasako$