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comp.lang.lisp

nice programming using pattern matching

Taoufik Dachraoui

5/24/2015 7:11:00 PM

Hi

I just implemented a setter "(setf (it x) value)" for the pattern matching tool I wrote a
long time ago; I would like to know if you agree that it is a nice tool for programming

; if first and last elements of the list are equal then set the LAST to 100
(match '(3 1 2 3) ((:and (:match (:or (?x) (_ . :self))) (?x . _)) (setf (it x) 100) it))
=> (3 1 2 100)

; if first and last elements of the list are equal then set the FIRST to 100
(match '(3 1 2 3) ((:and (?x . _) (:match (:or (?x) (_ . :self)))) (setf (it x) 100) it))
=> (100 1 2 3)


;;
? (defun foo (lst s)
(match lst ((:and (:match (:or (?x) (_ . :self))) (?x . _)) (setf (it x) s) it) (_ nil)))
FOO
? (foo '(1 2 3 4 1) 0)
(1 2 3 4 0)
? (foo '(1 2 3 4 5) 0)
NIL

- Taoufik
4 Answers

Taoufik Dachraoui

5/25/2015 7:15:00 PM

0

On Sunday, May 24, 2015 at 9:11:02 PM UTC+2, Taoufik Dachraoui wrote:
> Hi
>
> I just implemented a setter "(setf (it x) value)" for the pattern matching tool I wrote a
> long time ago; I would like to know if you agree that it is a nice tool for programming
>
> ; if first and last elements of the list are equal then set the LAST to 100
> (match '(3 1 2 3) ((:and (:match (:or (?x) (_ . :self))) (?x . _)) (setf (it x) 100) it))
> => (3 1 2 100)
>
> ; if first and last elements of the list are equal then set the FIRST to 100
> (match '(3 1 2 3) ((:and (?x . _) (:match (:or (?x) (_ . :self)))) (setf (it x) 100) it))
> => (100 1 2 3)
>
>
> ;;
> ? (defun foo (lst s)
> (match lst ((:and (:match (:or (?x) (_ . :self))) (?x . _)) (setf (it x) s) it) (_ nil)))
> FOO
> ? (foo '(1 2 3 4 1) 0)
> (1 2 3 4 0)
> ? (foo '(1 2 3 4 5) 0)
> NIL
>
> - Taoufik

How to write the following using loop or iterate:

? (match '(0 ((2 (0 1)) ((3 2) 1))) ((:or (:and (:type atom) (:adjoin test 'eq into ?x)) (:self :self)) x))
(0 2 1 3)

-Taoufik

Taoufik Dachraoui

5/25/2015 7:41:00 PM

0

On Sunday, May 24, 2015 at 9:11:02 PM UTC+2, Taoufik Dachraoui wrote:
> Hi
>
> I just implemented a setter "(setf (it x) value)" for the pattern matching tool I wrote a
> long time ago; I would like to know if you agree that it is a nice tool for programming
>
> ; if first and last elements of the list are equal then set the LAST to 100
> (match '(3 1 2 3) ((:and (:match (:or (?x) (_ . :self))) (?x . _)) (setf (it x) 100) it))
> => (3 1 2 100)
>
> ; if first and last elements of the list are equal then set the FIRST to 100
> (match '(3 1 2 3) ((:and (?x . _) (:match (:or (?x) (_ . :self)))) (setf (it x) 100) it))
> => (100 1 2 3)
>
>
> ;;
> ? (defun foo (lst s)
> (match lst ((:and (:match (:or (?x) (_ . :self))) (?x . _)) (setf (it x) s) it) (_ nil)))
> FOO
> ? (foo '(1 2 3 4 1) 0)
> (1 2 3 4 0)
> ? (foo '(1 2 3 4 5) 0)
> NIL
>
> - Taoufik

? defun foo (e) (match e ((:all-tree (:adjoin test 'eq into ?x)) x)))
FOO
? (foo '(0 ((2 (0 1)) ((3 2) 1))))
(0 2 1 3)

Taoufik Dachraoui

5/25/2015 7:47:00 PM

0

On Sunday, May 24, 2015 at 9:11:02 PM UTC+2, Taoufik Dachraoui wrote:
> Hi
>
> I just implemented a setter "(setf (it x) value)" for the pattern matching tool I wrote a
> long time ago; I would like to know if you agree that it is a nice tool for programming
>
> ; if first and last elements of the list are equal then set the LAST to 100
> (match '(3 1 2 3) ((:and (:match (:or (?x) (_ . :self))) (?x . _)) (setf (it x) 100) it))
> => (3 1 2 100)
>
> ; if first and last elements of the list are equal then set the FIRST to 100
> (match '(3 1 2 3) ((:and (?x . _) (:match (:or (?x) (_ . :self)))) (setf (it x) 100) it))
> => (100 1 2 3)
>
>
> ;;
> ? (defun foo (lst s)
> (match lst ((:and (:match (:or (?x) (_ . :self))) (?x . _)) (setf (it x) s) it) (_ nil)))
> FOO
> ? (foo '(1 2 3 4 1) 0)
> (1 2 3 4 0)
> ? (foo '(1 2 3 4 5) 0)
> NIL
>
> - Taoufik

? (match '(0 ((2 (0 1)) ((3 2) 1))) ((:all-tree (:adjoin test 'eq into ?x)) x))
(0 2 1 3)
? (match '(0 ((2 (0 1)) ((3 2) 1))) ((:all-tree (:collect into ?x)) x))
(0 2 0 1 3 2 1)
? (match '(0 ((2 (0 1)) ((3 2) 1))) ((:all-tree (:count into ?x)) x))
7
? (match '(0 ((2 (0 1)) ((3 2) 1))) ((:all-tree (:sum into ?x)) x))
9
? (match '(0 ((2 (0 1)) ((3 2) 1))) ((:all-tree (:max into ?x)) x))
3
? (match '(0 ((2 (0 1)) ((3 2) 1))) ((:all-tree (:min into ?x)) x))
0

William James

5/26/2015 7:54:00 AM

0

> How to write the following using loop or iterate:
>
> ? (match '(0 ((2 (0 1)) ((3 2) 1)))
> ((:or (:and (:type atom) (:adjoin test 'eq into ?x)) (:self :self)) x))
> (0 2 1 3)


Gauche Scheme:

(delete-duplicates (let go ((x '(0 ((2 (0 1)) ((3 2) 1)))))
(append-map (^x (if (list? x) (go x) (list x))) x)))
===>
(0 2 1 3)

Racket:

(require srfi/1)
(delete-duplicates (flatten '(0 ((2 (0 1)) ((3 2) 1)))))

MatzLisp:

[0, [[2, [0, 1]], [[3, 2], 1]]].flatten.uniq
==>[0, 2, 1, 3]

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