Search found 58 matches

by William James
Mon Oct 07, 2013 4:44 am
Forum: Whither newLISP?
Topic: lexical-let
Replies: 2
Views: 3284

lexical-let

Before version 24.1, EMACS Lisp was dynamically scoped; now lexical scoping is an option. When a closure was needed, it was customary to load the CL package and use lexical-let. It would be very nice if lexical-let were added to newLISP. Closures could be created more easily, by a method that is mor...
by William James
Sun Oct 06, 2013 7:50 am
Forum: newLISP in the real world
Topic: rewrite macros for updating association-lists
Replies: 1
Views: 685

rewrite macros for updating association-lists

(macro (assoc-push Alist Key Val) (let (key Key val Val) (or (catch (push val (or (lookup key Alist) (throw nil)) -1)) (push (list key (list val)) Alist -1)))) (macro (assoc++ Alist Key Val) (let (key Key val Val) (or (catch (++ (or (lookup key Alist) (throw nil)) (or val 1))) (push (list key (or v...
by William James
Fri Dec 28, 2012 8:53 pm
Forum: newLISP in the real world
Topic: Possible bug in sort
Replies: 4
Views: 799

Re: Possible bug in sort

I just tested the speed using Lutz's 'fun workaround. The composed function is just as fast as the lambda (fn (a b) (< (last a) (last b))) . Perhaps I should explain the name f<g= . If I remember correctly, J (descended from APL) gives names to its operators that compose functions like fork, atop, c...
by William James
Fri Dec 28, 2012 8:07 pm
Forum: newLISP in the real world
Topic: Possible bug in sort
Replies: 4
Views: 799

Re: Possible bug in sort

Thanks for the fast and helpful reply.

Function composition is a powerful and fun technique.
I'm hoping that

Code: Select all

(sort (copy test-list) (f<g= < last))
won't be slower than

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(sort (copy test-list) (fn (a b) (< (last a) (last b))))
by William James
Fri Dec 28, 2012 5:08 pm
Forum: newLISP in the real world
Topic: Possible bug in sort
Replies: 4
Views: 799

Possible bug in sort

;; Function composition. (define (f<g= f g) (expand (fn (a b) (f (g a) (g b))) 'f 'g)) ((f<g= < last) '(a 2) '(b 3)) ==> true ((f<g= < last) '(b 3) '(a 2)) ==> nil (set 'lst '((b 5) (a 2))) (sort lst (f<g= < last)) ==> ((a 2) (b 5)) (set 'lst '((a 2) (b 5))) (sort lst (f<g= < last)) ==> ((a 2) (b 5...
by William James
Thu Dec 27, 2012 12:12 pm
Forum: Anything else we might add?
Topic: wish i could enter multiline expressions by default
Replies: 10
Views: 2695

Re: wish i could enter multiline expressions by default

Here's a REPL that I cobbled together. It probably has bugs, but it works pretty well for me. (println "Quit with (exit).") (define (input__complete? str) (if (or (find "^\s*$" str 0) (find "^\s*;[^\n]*$" str 0)) true (let (error-message "" scanned 0) (if (catch (begin (read-expr str) (setq scanned ...
by William James
Fri Dec 21, 2012 3:33 pm
Forum: newLISP in the real world
Topic: Is there an equivalent to flet or labels?
Replies: 7
Views: 1202

Re: Is there an equivalent to flet or labels?

Code: Select all

> (set 'a (fn (n) (if (zero? n) 1 (* n (a (- n 1))))))
(lambda (n)
 (if (zero? n)
  1
  (* n (a (- n 1)))))
> (a 5)
120
by William James
Fri Dec 21, 2012 3:11 pm
Forum: newLISP in the real world
Topic: list to values
Replies: 4
Views: 895

Re: list to values

Code: Select all

(define (my-func s1 s2 a b c)
  (dup (string s1 s2 a b) c))

> (my-func "o" "-" 1984 9 3)
"o-19849o-19849o-19849"

> (apply my-func (cons "o" (cons "-" '(1984 9 3))))
"o-19849o-19849o-19849"

> (apply my-func (append '("o" "-") '(1984 9 3)))
"o-19849o-19849o-19849"
by William James
Fri Dec 21, 2012 2:47 pm
Forum: newLISP in the real world
Topic: Use map to process list of lines from stdin?
Replies: 4
Views: 986

Re: Use map to process list of lines from stdin?

Code: Select all

(define (half-string str)
  ((div (length str) 2) str))

(while (read-line)
  (println (half-string (current-line))))
by William James
Tue Apr 10, 2012 5:03 pm
Forum: newLISP in the real world
Topic: Pseudo-closures using gensym
Replies: 5
Views: 1082

Re: Pseudo-closures using gensym

It seems that gensym isn't really needed anymore.

One can simply do (sym (uuid)).
by William James
Mon Apr 09, 2012 10:52 pm
Forum: Anything else we might add?
Topic: escaping characters problem
Replies: 10
Views: 4755

Re: escaping characters problem

I'm processing some text so that various characters are replaced with alternative formulations. The problem is that the curly braces in the original text need to be replaced with \letteropenbrace{} but the backslashes need to be replaced with \letterbackslash{}, and I can't do both these operations...
by William James
Sun Apr 08, 2012 11:05 pm
Forum: newLISP in the real world
Topic: Some minor errors about manual and ....
Replies: 7
Views: 1411

Re: Some minor errors about manual and ....

Code: Select all

;; using sym for simulating hash tables

(set (sym "John Doe" 'MyDB') 1.234)
There should not be a single-quote after 'MyDB.
by William James
Sun Apr 08, 2012 12:28 am
Forum: newLISP in the real world
Topic: Macros for pipelining
Replies: 2
Views: 735

Re: Macros for pipelining

Interesting approach; I'm not very familiar with letex. Since we are putting each macro in its own context, I think you can safely use func instead of _func. I like "(if $args" instead of "(if (empty? (args))"; shorter and cleaner. You gave me the idea of just using one eval : (context '->>) (define...
by William James
Sat Apr 07, 2012 4:35 pm
Forum: newLISP in the real world
Topic: Macros for pipelining
Replies: 2
Views: 735

Macros for pipelining

Here are two "threading" or pipelining macros, similar to those in Clojure: (context '->>) (define-macro (->>:->> E form) (if (empty? (args)) (if (list? form) (eval (push E form -1)) (eval (list form E))) (eval (cons '->> (cons (list '->> E form) (args)))))) (context '->) (define-macro (->:-> E form...
by William James
Sat Apr 07, 2012 1:52 pm
Forum: newLISP in the real world
Topic: Yet another REPL
Replies: 1
Views: 513

Re: Yet another REPL

Slightly improved. To quit, type "(exit)". (define (input__complete? str) (if (or (find "^\s*$" str 0) (find "^\s*;[^\n]*$" str 0)) true (let (error-message "" scanned 0) (if (catch (begin (read-expr str) (setq scanned $0)) 'error-message) (input__complete? (slice str scanned)) (when (find {^ERR: sy...
by William James
Wed Apr 04, 2012 10:17 pm
Forum: newLISP in the real world
Topic: Yet another REPL
Replies: 1
Views: 513

Yet another REPL

Allows you to spread your expressions over several lines. : ( factor 99999999991 ) (83 1289 934693) If botched input keeps the prompt from appearing, control-Z (under Windows; for Linux, try control-D) should clear up the problem: : * 2 3) ) ) ^Z ERR: string expected : nil A work in progress. Modify...
by William James
Wed Apr 04, 2012 8:49 pm
Forum: newLISP in the real world
Topic: Pseudo-closures using gensym
Replies: 5
Views: 1082

Re: Pseudo-closures using gensym

Thanks. I think it would be nice if gensym were built into newLISP.
by William James
Wed Apr 04, 2012 2:22 pm
Forum: newLISP in the real world
Topic: Pseudo-closures using gensym
Replies: 5
Views: 1082

Re: Pseudo-closures using gensym

Slightly improved, and with an example in which two lambdas share a variable. (define-macro (closure varval-pairs) (let (body (cons 'begin (args)) alist (map (fn(x) (list (x 0) (gensym) (eval (x 1)))) (explode varval-pairs 2))) (bind (map (fn (x) (rest x)) alist)) (dolist (x alist) (set-ref-all (x 0...
by William James
Sun Apr 01, 2012 3:39 pm
Forum: newLISP in the real world
Topic: Pseudo-closures using gensym
Replies: 5
Views: 1082

Pseudo-closures using gensym

(define (gensym:gensym) (sym (string "gensym-" (inc gensym:counter)))) (define-macro (closure varval-pairs body) (let (alist (map (fn(x) (list (x 0) (gensym) (eval (x 1)))) (explode varval-pairs 2))) (bind (map (fn (x) (rest x)) alist)) (dolist (x alist) (set-ref-all (x 0) body (x 1))) body)) (set ...
by William James
Fri Mar 09, 2012 1:59 am
Forum: newLISP in the real world
Topic: Set Operations
Replies: 4
Views: 799

Re: Set Operations

Kazimir Majorinc wrote:I agree about union, not because it is particularly missing, but because it is low hanging fruit.
Good news, Kazimir. Lutz sent me a p.m. indicating that this will be added.
by William James
Thu Mar 08, 2012 2:45 am
Forum: newLISP in the real world
Topic: dolist but getting more values at the same time
Replies: 18
Views: 2404

Re: dolist but getting more values at the same time

I enjoy using the int-reduce option in apply.
When int-reduce is 2, the behavior is like fold or reduce; when it's larger than 2, it's even more fun.

Code: Select all

> (apply (fn(_ a b c)(println a b c)) (cons nil (sequence 1 9)) 4)
123
456
789
by William James
Wed Mar 07, 2012 9:13 pm
Forum: Whither newLISP?
Topic: extract analogous to extend?
Replies: 6
Views: 4852

Re: extract analogous to extend?

rickyboy wrote:Don't know about Scheme, but in SBCL:

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* (mapc #'set '(ee ff gg) '(22 33 44))
(EE FF GG)
* ee
22
* ff
33
* gg
44
Yes, I later realized that. My post has been corrected.
by William James
Wed Mar 07, 2012 10:12 am
Forum: Whither newLISP?
Topic: extract analogous to extend?
Replies: 6
Views: 4852

Re: extract analogous to extend?

I never thought of

Code: Select all

(map set '(a b c) '(1 2 3))
... probably because it's not allowed in other languages.

Gambit Scheme:

Code: Select all

4> (map define '(ee ff gg) '(22 33 44))
*** ERROR IN (console)@8.6 -- Macro name can't be used as a variable: define
by William James
Tue Mar 06, 2012 9:30 am
Forum: Anything else we might add?
Topic: all? or perhaps predicates that accept multiple args
Replies: 4
Views: 2026

Re: all? or perhaps predicates that accept multiple args

This works for me:

Code: Select all

(define (for-all-args func)
  (for-all func (args)))

> (for-all-args number? 2 3 4 5)
true

> (for-all-args number? 2 3 'not 5)
nil
by William James
Tue Mar 06, 2012 6:52 am
Forum: newLISP in the real world
Topic: Function composition?
Replies: 4
Views: 966

Re: Function composition?

These seem to work. ;; Compose two functions. Both accept only 1 argument. (define (atop f g) (expand (lambda (a) (f (g a))) 'f 'g)) ;; Compose two functions. The first to be called accepts ;; any number of arguments. (define (atop* f g) (expand (lambda () (f (apply g (args)))) 'f 'g)) Thanks to Kaz...