Re: Mini http server
Hi Henrik, The goal is also to have something that can be loaded after/instead of http.l when you want a simple web server without the fancy stuff. OK. (redef httpHead (Typ Upd File Att) (http1 Typ Upd File Att) (and *Chunked (prinl Transfer-Encoding: chunked^M)) (prinl ^M) ) This is basically correct, and should work, but it is not really what 'redef' is intended for. 'redef' redefines a function in terms of _itself_, i.e. you can use the original function inside the new one. For clarity, I would recommend for the above case, where a function is re-defined from scratch, the sequence (undef 'httpHead) (de 'httpHead .. Also, redefining 'httpHead' is probably not necessary. The difference is only the output of cookies, but this won't happen if no cookies are set. (redef http (S) Concerning the contents, still more simplifications might be possible. Also, it seems that you based your port on a rather old version of lib/http.l. So here are some points (surely not complete) (use (*Post L @U @H @X) (off *Post *ContLen *Cookies *Cookies *HtSet) (catch http (in S (cond ((not (setq L (line))) (close S) (task S) (off S) (throw http) ) ((match '(G E T / @U H T T P / 1 . @H) L) (_htHead) (setq *Get T) (setq L (split @U ?)) (for KeyVal (split (cadr L) ) (let Res (split KeyVal =) (put '*Get (pack (car Res)) (ht:Pack (cadr Res))) ) ) ) ((match '(P O S T / @U H T T P / 1 . @H) L) (setq *Post T) (on *Post) (off *MPartLim *MPartEnd) (_htHead) (cond (*MPartLim (_htMultipart)) ((if *ContLen (ht:Read @) (line)) (for L (split @ ') (when (cdr (setq L (split L =))) (put '*Post (pack (car L)) (ht:Pack (cadr L))) ) ) ) (T (throw http)) ) ) (T (out S (if (and (match '(@U @ H T T P . @) L) (member @U (quote (O P T I O N S) (H E A D) (P U T) (D E L E T E) (T R A C E) (C O N N E C T) ) ) ) (httpStat 501 Method Not Implemented Allow: GET, POST) (httpStat 400 Bad Request) ) ) (close S) (task S) (off S) (throw http) ) ) (out S (cond ((match '(- @X . h t m l) @U) (try 'html (extern (ht:Pack @X))) ) This clause is probably not needed, as it addresses database objects which have a 'html' method defined. ((= '@ (car @U)) (apply (val (intern (ht:Pack (cdr @U L) ) ((tail '(. l) @U) (apply script L *Url) ) ((assoc (stem @U .) *Mimes) (apply httpEcho (cdr @) *Url) ) Does the '*Mimes' global exist? ((=T (car (info *Url))) (if (info (setq *Url (pack *Url default))) (apply script L *Url) (http404) ) ) This clause is probably also not necessary. It is used only if a directory should have a default script. (T (httpEcho *Url application/octet-stream 1 T)) ) ) ) ) (and S (=0 *Http1) (close S) (task S)) ) ) Cheers, - Alex -- UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe
pilog: unification in variables that are clauses
--- On Wed, 6/29/11, Alexander Burger a...@software-lab.de wrote: So this should be written as (be holds (@A @S) (or ((restoreSitArg @A @S @F) (@ solve (list (- @F ((not (restoreSitArg @A @S @F)) (isAtom @A) (@ solve (list (- @A ) ) holds(A,S) :- restoreSitArg(A,S,F), F ; \+ restoreSitArg(A,S,F), isAtom(A), A. Now I think that the variables-as-clauses are getting me. In this rule, F might get bound to (unified with?) a clause with variables. For example, F might be bound to something like on(N,s0) When the F clause (now bound to on(N,s0)) is then proved, the N variable in on(N,s0) gets bound to something (3, for example). [trace] ?- holds(on(N), s0 ). Call: (6) holds(on(_G386), s0) ? creep Call: (7) restoreSitArg(on(_G386), s0, _G462) ? creep Exit: (7) restoreSitArg(on(_G386), s0, on(_G386, s0)) ? creep Call: (7) on(_G386, s0) ? creep Exit: (7) on(3, s0) ? creep Exit: (6) holds(on(3), s0) ? creep N = 3 . When I try to do this as (@ (solve (list (- @F in pilog, taking it through lisp , it prevents the values of the unified vars in @F from being used in the surrounding pilog rule. ? (? (holds (On @N) s0)) - T ? (solve '((holds (On @N) s0))) - (T) I wonder what I should do in this case, where a variable can be bound to a clause like that and the variables in that clause need to be bound, too? Cheers, Doug -- UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe
Re: pilog: unification in variables that are clauses
Hi Doug,
So this should be written as
(be holds (@A @S)
(or
((restoreSitArg @A @S @F) (@ solve (list (- @F
((not (restoreSitArg @A @S @F)) (isAtom @A) (@ solve (list (- @A ) )
I didn't test it, but I think the construct using 'solve' is more
complicated than necessary.
At least, a simple (@ . @A) should work. Doesn't it?
In any case, I'm wondering why this problems exists. Usually, variables
are not unified with NIL during normal processing. How comes that this
happens with '@A'?
When I try to do this as (@ (solve (list (- @F in pilog, taking
Note that the '(' before 'solve' is not correct. In the example above
you have it right, though.
I wonder what I should do in this case, where a variable can be bound
to a clause like that and the variables in that clause need to be bound,
too?
I would believe that this case is quite common.
I must confess that I don't remember the details very well, but some
system predicates in lib/pilog.l do similar things.
For example the 'not', 'call' and 'or' predicates evaluate argument
clauses, including unification etc. The syntactic element in Pilog for
that is that the clause starts with a number (as opposed to a symbol for
normal clauses, and a @Variable for Lisp expressions). Then that
number specifies the nth surrounding environment where that clause is to
be unified in.
Perhaps it is even enough in your case, if you use 'call'?
Cheers,
- Alex
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Re: pilog: unification in variables that are clauses
On Thu, Jun 30, 2011 at 09:20:43AM +0200, Alexander Burger wrote: At least, a simple (@ . @A) should work. Doesn't it? Wait ... probably not a good idea. But this should work: (@ - @A) -- UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe
Re: pilog: unification in variables that are clauses
Hi Alex, Thanks for your help! holds(A,S) :- restoreSitArg(A,S,F), F ; \+ restoreSitArg(A,S,F), isAtom(A), A. What I really want is this: (be holds (@A @S) (or ((restoreSitArg @A @S @F) @F) ((not (restoreSitArg @A @S @F)) (isAtom @A) @A) ) ) But the above (with a @F or @A for a clause) doesn't work. :-( This - (be holds (@A @S) (or ((restoreSitArg @A @S @F) (@ - @F)) ((not (restoreSitArg @A @S @F)) (isAtom @A) (@ - @A)) ) ) gives me the same results as using the (@ solve (list (- @F))) clause. Neither that nor (@ - @F) seem to unify variables in @F (which is bound to a clause) : (solve '((holds (On @N) s0))) - (T) Solves, but it also should tell me @N is bound to 3 Cheers, Doug --- On Thu, 6/30/11, Alexander Burger a...@software-lab.de wrote: From: Alexander Burger a...@software-lab.de Subject: Re: pilog: unification in variables that are clauses To: picolisp@software-lab.de Date: Thursday, June 30, 2011, 12:27 AM On Thu, Jun 30, 2011 at 09:20:43AM +0200, Alexander Burger wrote: At least, a simple (@ . @A) should work. Doesn't it? Wait ... probably not a good idea. But this should work: (@ - @A) -- UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe -- UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe
Re: pilog: unification in variables that are clauses
Hi Doug, (be holds (@A @S) (or ((restoreSitArg @A @S @F) (@ - @F)) ((not (restoreSitArg @A @S @F)) (isAtom @A) (@ - @A)) ) ) gives me the same results as using the (@ solve (list (- @F))) clause. Neither that nor (@ - @F) seem to unify variables in @F (which is bound to a clause) (@ - @F) just matches locally, without binding variables. What happens if you use (@F - @F) or (@A - @A)? This will unify the variable with its Lisp value. Or did I understand right that @F and/or @A contain another Pilog clause? Then: Can't you use (call @A), as I wrote in my last mail? I still don't understand why this test of @A and/or @F for being non-NIL is necessary at all. This looks unusual to me. On the other hand, I'm a really poor Prolog programmer ... Cheers, - Alex -- UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe
interesting observations about bugs
http://itunes.apple.com/ca/podcast/the-stack-exchange-podcast/id279215411
Re: Picked from HN: `First-class environments.'
Hi dexen + all, I accepted the challenge, and posted a new task to RosettaCode: http://rosettacode.org/wiki/First_class_environments The PicoLisp solution is quite clean, IMHO. Cheers, - Alex -- UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe
Re: pilog: unification in variables that are clauses
Here's the issue boiled down to a simpler test case :-) First, swi-prolog: # cat t.pl a(3). foo(N) :- N. bar(a(X)) :- a(X). # swipl -f t.pl % /root/prolog/t.pl compiled 0.00 sec, 2,800 bytes ... ?- trace. true. [trace] ?- bar(a(Z)). Call: (6) bar(a(_G386)) ? creep Call: (7) a(_G386) ? creep Exit: (7) a(3) ? creep Exit: (6) bar(a(3)) ? creep Z = 3. [trace] ?- foo(a(Z)). Call: (6) foo(a(_G386)) ? creep Call: (7) a(_G386) ? creep Exit: (7) a(3) ? creep Exit: (6) foo(a(3)) ? creep Z = 3. In both cases, Z is correctly bound to 3. (The foo rule is the one we are interested in.) $ cat t.l (be a (3)) (be foo (@C) (@C - @C)) (be bar ((a @N)) (a @N)) ~/lisp/miniPicoLisp $ ./pil t.l : (? a bar (bar (a @X))) 1 (bar (a @N)) 1 (a 3) @X=3 - NIL That is correct: @X=3 ... however : : (? a foo (foo (a @X))) 1 (foo (a @X)) @X=NIL - NIL : But they should be the same, as @X = 3 is a (is the) solution. Moreover, in foo (a @X) is never even tried to be proven. So I think this test case demonstrates the issue. I still don't understand why this test of @A and/or @F for being non-NIL is necessary at all. This looks unusual to me. holds(A,S) :- restoreSitArg(A,S,F), F ; \+ restoreSitArg(A,S,F), isAtom(A), A. Me too. At first, I also thought they simply were testing for non-NIL there. But the intent of the 'naked' F and A clauses there seems to be this: If the data bound to F (or A) is itself a clause, then that clause gets proved and variables in it get unified/bound. So after the first restoreSitArg(A,S,F), F starts out as partially bound to a clause like on(N,s0) - which itself has an unbound variable, N. After F is proven, N is bound to 3 (because on(3,s0) is asserted elsewhere, and so N = 3 is a solution). A bit tricky, with variables bound to clauses which, in turn, have in them other unbound variables that may get bound. Using call/1 there (not sure if this is the way I should use it) gives similar results, where (a @X) is not attempted to be proven. $ cat t.l (be a (3)) (be foo (@C) # (@C - @C)) (call @C)) ~/lisp/miniPicoLisp $ ./pil t.l : (? a foo call (foo (a @X))) 1 (foo (a @X)) 1 (call (a @X)) - NIL : Cheers, Doug -- UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe
Re: Picked from HN: `First-class environments.'
Nice! I like that site rosettacode.org lots. (I stopped counting how many computer 'languages' I have assimilated over the years!) This example again shows off picolisp/pilog nicely. http://rosettacode.org/wiki/24_game/Solve#PicoLisp I think the perl solution may be a tad smaller. But most of us can't scan the perl one easily - the perl example there is dense and appears to be obfuscated. The picolisp/pilog example is not obfuscated and is smooth and clean IMO. :-) --- On Thu, 6/30/11, Alexander Burger a...@software-lab.de wrote: From: Alexander Burger a...@software-lab.de Subject: Re: Picked from HN: `First-class environments.' To: picolisp@software-lab.de Date: Thursday, June 30, 2011, 5:50 AM Hi dexen + all, I accepted the challenge, and posted a new task to RosettaCode: http://rosettacode.org/wiki/First_class_environments The PicoLisp solution is quite clean, IMHO. Cheers, - Alex -- UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe -- UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe
Re: pilog: unification in variables that are clauses
The solve way seems to some closest to doing it. ~/lisp/miniPicoLisp $ cat t.l (be a (3)) (be foo (@C) # (@C - @C) # (call @C) (@ print (solve (list (- @C ) $ ./pil t.l : (? a foo (foo (a @Z))) 1 (foo (a @Z)) (((@Z . 3)))- T So I can see that it is correctly solving for @Z this way. But it doesn't take that binding (@Z = 3) back into the foo rule. -- UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe
