Some Scheme file.scm

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; GLOBAL AUXILIARY FUNCS, before working on real project code ;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

; first, convert to Haskel-ish notations
(require srfi/1)
(define (oldtake l n) (take l n))
(define (olddrop l n) (drop l n))

; Haskell-ish take and drop
(define (take n l) (oldtake l n))
(define (drop n l) (olddrop l n))

; safe call of car -> returns '() if there's no answer
(define (head l) (if (null? l) '() (car l)))

; nubify = remove duplicates
(define (nub l) (reverse (nub-aux l '())))

; repeat
(define (repeat x n) (if (>= 0 n) '() (cons x (repeat x (- n 1)))))

; Haskell-ish append, used below to implement set addition
(define ++ (lambda l (apply append l)))
(define +++ (lambda l (nub (apply ++ l))))