June 2008 - cl-unification-devel - mailman3.common-lisp.net

Re: [cl-unification-devel] a simpler example
by Russell McManus 12 Jun '08

12 Jun '08

I tried the attached version, and the problem persists. Thanks for looking into it, -russ ----- Original Message ---- > From: Marco Antoniotti <marcoxa(a)cs.nyu.edu> > To: cl-unification-devel(a)common-lisp.net > Cc: Russell McManus <russell_mcmanus(a)yahoo.com> > Sent: Wednesday, June 11, 2008 11:02:56 AM > Subject: Re: [cl-unification-devel] a simpler example > > There may be a misalignment with my version (which works on LW) and > the CVS version, or it may be a problem which SBCL raises due to its > version (more strict) of MAKE-LOAD-FORM. > > I'll look into it. > > Thanks for raising the issue. > > Meanwhile try the version attached on SBCL. > > Cheers > -- > Marco > > > > > > > On Jun 11, 2008, at 16:04 , Russell McManus wrote: > > > I'm pretty sure that I tried repeating the #T before sending my > > first email, but it failed with an error. > > > > I just tried again on sbcl 1.0.10.16 and got the following: > > > > (unify #T(list ?f #T(list ?s1 ?s2)) '(a (b c))) > > > > > > Cannot unify two different symbols: B MAKE-TEMPLATE. > > [Condition of type CL.EXT.DACF.UNIFICATION::UNIFICATION-FAILURE] > > > > Restarts: > > 0: [ABORT] Return to SLIME's top level. > > 1: [TERMINATE-THREAD] Terminate this thread (# > > "worker" {1008AB0C91}>) > > > > Any ideas what I should try next? > > > > -russ > > > > > > > > ----- Original Message ---- > >> From: Marco Antoniotti > >> To: cl-unification-devel(a)common-lisp.net > >> Sent: Tuesday, June 10, 2008 3:51:44 AM > >> Subject: Re: [cl-unification-devel] a simpler example > >> > >> > >> On Jun 6, 2008, at 24:38 , Russell McManus wrote: > >> > >>> > >>> Here are some examples: > >>> > >>> ;; this works > >>> (find-variable-value > >>> '?s > >>> (unify #T(list ?f ?s) '(a (b c)))) > >> > >> Yes. > >> > >>> > >>> ;; this works > >>> (find-variable-value > >>> '?s1 > >>> (unify #T(list ?f (?s1 ?s2)) '(a (b c)))) > >> > >> Yes. > >> > >> > >>> > >>> ;; this fails > >>> (find-variable-value > >>> '?s1 > >>> (unify #T(list ?f (list ?s1 ?s2)) '(a (b c)))) > >> > >> As it should. What you want is > >> > >> (unify #T(list ?f #T(list ?s1 ?s2)) '(a (b c))) > >> > >> In your case you are trying to unify a template of type LIST with a > >> variable in FIRST and a list (LIST ?s1 ?s2) in SECOND. The second > >> element cannot unify with (B C), hence the failure. > >> > >>> > >>> I was expecting the meaning of LIST to be the same whether > >>> it is encountered at top level in a template, or at a nested level. > >>> > >>> Is this a bug, or are my expectations wrong? > >> > >> Sorry. It is your expectations. If you look at the most general > >> syntax for templates, you will see that it is #T(. > >> ). This is because it would be a nightmare to do otherwise. > >> > >> > >> Suppose you have a > >> > >> (unify #T(list 42 (foo)) (list 42 (list 'foo))) > >> > >> should unify. But is next you do > >> > >> (defstruct foo a s d) > >> > >> then > >> > >> (unify #T(list 42 (foo)) (list 42 (list 'foo))) > >> > >> may or may not unify pending interpretation. > >> > >> Hope this clarifies things. Let me know if there are other pitfalls > >> or bugs in the code. > >> > >> Cheers > >> > >> Marco > >> > >> > >>> > >> > >> -- > >> Marco Antoniotti > >> > >> > >> _______________________________________________ > >> cl-unification-devel site list > >> cl-unification-devel(a)common-lisp.net > >> http://common-lisp.net/mailman/listinfo/cl-unification-devel > > > > -- > Marco Antoniotti

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Re: [cl-unification-devel] a simpler example
by Russell McManus 11 Jun '08

11 Jun '08

I'm pretty sure that I tried repeating the #T before sending my first email, but it failed with an error. I just tried again on sbcl 1.0.10.16 and got the following: (unify #T(list ?f #T(list ?s1 ?s2)) '(a (b c))) Cannot unify two different symbols: B MAKE-TEMPLATE. [Condition of type CL.EXT.DACF.UNIFICATION::UNIFICATION-FAILURE] Restarts: 0: [ABORT] Return to SLIME's top level. 1: [TERMINATE-THREAD] Terminate this thread (#<THREAD "worker" {1008AB0C91}>) Any ideas what I should try next? -russ ----- Original Message ---- > From: Marco Antoniotti <marcoxa(a)cs.nyu.edu> > To: cl-unification-devel(a)common-lisp.net > Sent: Tuesday, June 10, 2008 3:51:44 AM > Subject: Re: [cl-unification-devel] a simpler example > > > On Jun 6, 2008, at 24:38 , Russell McManus wrote: > > > > > Here are some examples: > > > > ;; this works > > (find-variable-value > > '?s > > (unify #T(list ?f ?s) '(a (b c)))) > > Yes. > > > > > ;; this works > > (find-variable-value > > '?s1 > > (unify #T(list ?f (?s1 ?s2)) '(a (b c)))) > > Yes. > > > > > > ;; this fails > > (find-variable-value > > '?s1 > > (unify #T(list ?f (list ?s1 ?s2)) '(a (b c)))) > > As it should. What you want is > > (unify #T(list ?f #T(list ?s1 ?s2)) '(a (b c))) > > In your case you are trying to unify a template of type LIST with a > variable in FIRST and a list (LIST ?s1 ?s2) in SECOND. The second > element cannot unify with (B C), hence the failure. > > > > > I was expecting the meaning of LIST to be the same whether > > it is encountered at top level in a template, or at a nested level. > > > > Is this a bug, or are my expectations wrong? > > Sorry. It is your expectations. If you look at the most general > syntax for templates, you will see that it is #T(. > ). This is because it would be a nightmare to do otherwise. > > > Suppose you have a > > (unify #T(list 42 (foo)) (list 42 (list 'foo))) > > should unify. But is next you do > > (defstruct foo a s d) > > then > > (unify #T(list 42 (foo)) (list 42 (list 'foo))) > > may or may not unify pending interpretation. > > Hope this clarifies things. Let me know if there are other pitfalls > or bugs in the code. > > Cheers > > Marco > > > > > > -- > Marco Antoniotti > > > _______________________________________________ > cl-unification-devel site list > cl-unification-devel(a)common-lisp.net > http://common-lisp.net/mailman/listinfo/cl-unification-devel

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[cl-unification-devel] a simpler example
by Russell McManus 10 Jun '08

10 Jun '08

Here are some examples: ;; this works (find-variable-value '?s (unify #T(list ?f ?s) '(a (b c)))) ;; this works (find-variable-value '?s1 (unify #T(list ?f (?s1 ?s2)) '(a (b c)))) ;; this fails (find-variable-value '?s1 (unify #T(list ?f (list ?s1 ?s2)) '(a (b c)))) I was expecting the meaning of LIST to be the same whether it is encountered at top level in a template, or at a nested level. Is this a bug, or are my expectations wrong? -russ

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[cl-unification-devel] simple question
by Russell McManus 05 Jun '08

05 Jun '08

I'm just learning how to use cl-unification. I have written some code that doesn't work the way I expect, but of course this probably means that my expectations are wrong. Can one of the cl-unification gurus take a look, and let me know what I'm doing wrong? Thanks, -russ (defpackage :unification-demo (:use :cl :CL.EXT.DACF.UNIFICATION)) (in-package :unification-demo) (declaim (optimize (debug 3) (speed 0))) (defclass call-expr () ((rator :reader rator) (rands :reader rands))) (defmethod initialize-instance :after ((call-expr call-expr) &key form) (with-slots (rator rands) call-expr (destructuring-bind (rator-form &rest rand-forms) form (setf rator rator-form rands (mapcar (lambda (rand-form) (parse-expr rand-form)) rand-forms))))) (defclass var-ref () ((var :initarg :var :reader var))) (defclass let-binding () ((var :reader let-binding-var :initarg :var) (expr :reader let-binding-expr :initarg :expr))) (defmethod initialize-instance :after ((let-binding let-binding) &key form) (with-slots (var expr) let-binding (destructuring-bind (var-form expr-form) form (setf var var-form expr (parse-expr expr-form))))) (defclass let-expr () ((bindings :reader bindings) (body :reader body))) (defmethod initialize-instance :after ((let-expr let-expr) &key form) (with-slots (bindings body) let-expr (destructuring-bind (binding-forms body-form) (cdr form) (setf bindings (mapcar (lambda (form) (make-instance 'let-binding :form form)) binding-forms) body (parse-expr body-form))))) (defun parse-expr (form) (flet ((car-match (indicator) (and (consp form) (eql (car form) indicator))) (constant-match () (or (stringp form) (numberp form)))) (cond ((constant-match) form) ((car-match 'let) (make-instance 'let-expr :form form)) ((car-match 'lambda) (make-instance 'lambda-expr :form form)) ((consp form) (make-instance 'call-expr :form form)) ((symbolp form) (make-instance 'var-ref :var form)) (t (error "unhandled form ~A" form))))) ;; this works (find-variable-value '?bs (unify #T(let-expr bindings ?bs) (parse-expr '(let ((x 1) (y 2)) (+ x y))))) ;; this fails, why? (find-variable-value '?b (unify #T(let-expr bindings (list ?b &rest ?bs)) (parse-expr '(let ((x 1) (y 2)) (+ x y)))))

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