Mastermind setter (scheme) and flibug meeting

Mastermind setter
Last week, I couldn't work on the mastermind solver, but at least, I finished the setter.

It was a good exercice to get in touch with scheme IO, like getting input from user, split strings, and the like.

I finally removed all the functions for IO, because I can supply the inputs as lists on the REPL. I've used drscheme, but as this week I also tried guile (embeding it in a c app. Pretty cool), I might try it for future hacks.

(check-sols '(1 2) '(1 3))

I'm quite excited about how easy it became to do it, and this weekend I'll spend some time on the solver.

	#lang scheme
	(define (sum l) (foldl + 0 l))
	(define max 5)
	(define sol (solution 4 5))
	(define (solution num max)
	(define (sol num max l)
	(cond ((zero? num) l)
	(else (sol (- num 1) max (cons (random max) l)))))
	(sol num max '()))
	;; returns how many blacks
	(define (blacks l1 l2)
	(define (my-blacks l1 l2 res)
	(cond ((null? l1) res)
	((= (car l1) (car l2)) (my-blacks (cdr l1)
	(cdr l2)
	(+ res 1)))
	(else (my-blacks (cdr l1) (cdr l2) res))))
	(my-blacks l1 l2 0))
	;; counts how many whites should go,
	;; without looking @ positions, so
	;; counting blacks as whites too
	(define (whites l1 l2)
	(define (minim x l1 l2)
	(min (length (filter (lambda (y) (= y x)) l1))
	(length (filter (lambda (y) (= y x)) l2))))
	(define (my-whites l1 l2 res)
	(sum (map (lambda (x) (minim x l1 l2))
	(build-list max values))))
	(my-whites l1 l2 0))
	(define (check-sols my-sol l2)
	(let* ((black (blacks my-sol l2))
	(white (- (whites my-sol l2) black)))
	(string-append
	(make-string black #\B)
	(make-string white #\W))))
	(define (check-real l)
	(check-sols l sol))

view raw mastermind-solver.scm hosted with ❤ by GitHub

flibug
On the other side, this tuesday we had another flibug meeting at oblong. Amazing, as always:

• Aleix Conchillo made a live presentation about plt slideshow. A module to create slides using scheme. Given that I had invested some time to find a good slides maker and not finding it, this might be a good solution to study further.
• Andy Wingo showed us a demo of the greatest technology I've seen in many many many (sorry) months. When I arrived home I said "Papa,mama, I'm back from the future".
  
• Colin Fleming made a good (also with live demos) presentation about IntelliJ refactoring tools, and he expressed his feeling of the need for clever programing environments. It's impressive how an IDE parses your code, and how much it knows about good/bad practices and hints you with improvements. He started coding a scheme mode for this IDE that already managed some refactorings like var renaming. As editors are a religion matter, some of the assistants had a few doubts of the real benefits of using a 'cool' boxed IDE (although extensible) versus using a swissknife-and-the-kitchen-sink emacs. On my part, being a vim user for 4 years and just starting to dip in emacs, I'll follow this thread really close.

I'd like to thank all the flibuggers and oblong for sharing all that coolness. I wish I could share more with them giving something back (with a presentation). Maybe when I finish my degree project I can prepare something about stumpwm or fluxus.

I'd say it's been a pretty exciting scheme-y week.