more functional approach

main
Inga 🏳‍🌈 11 months ago
parent 7e979bb2cf
commit 80aa85f17b
  1. 67
      day01-easy/main.scm

@ -10,51 +10,46 @@
'() '()
(cons line (loop (read-line)))))) (cons line (loop (read-line))))))
(define (reduce-right reducer initial list) (define (id value) value)
(if
(null? list)
initial
(reducer (car list) (reduce-right reducer initial (cdr list)))))
(define (map mapper list) (define (compose result-transformer f argument-transformer)
(lambda (value)
(result-transformer (f (argument-transformer value)))))
(define Y (lambda (f) (f (lambda (x) ((Y f) x)))))
(define (reduce-right reducer initial) (Y
(lambda (f) (lambda (list)
(if (null? list) initial (reducer (car list) (f (cdr list))))))))
(define (map mapper)
(reduce-right (reduce-right
(lambda (current accumulator) (cons (mapper current) accumulator)) (lambda (current accumulator) (cons (mapper current) accumulator))
'() '()))
list))
(define (combine combiner a b) (define (combine combiner)
(if (null? a) b (if (null? b) a (combiner a b)))) (lambda (a b) (if (null? a) b (if (null? b) a (combiner a b)))))
(define (sum numbers) (reduce-right + 0 numbers)) (define sum (reduce-right + 0))
(define (define (repeat value) (Y
(repeat value number) (lambda (f) (lambda (n)
(if (if (= n 0) '() (cons value (f (- n 1))))))))
(= number 0)
'()
(cons value (repeat value (- number 1)))))
(define (is-numeric-char char) (if (char-numeric? char) #t #f)) (define (is-numeric-char char) (if (char-numeric? char) #t #f))
(define (first-last predicate list) (define (first-last predicate) (compose
id
(reduce-right (reduce-right
(lambda (current accumulator) (combine (lambda (left right) (cons (car left) (cdr right))))
(combine '())
(lambda (left right) (cons (car left) (cdr right))) (map (lambda (entry) (if (predicate entry) ((repeat entry) 2) '())))))
current
accumulator)) (define solve-line (compose
'() (lambda (first-last-result) (string->number (list->string first-last-result)))
(map (first-last is-numeric-char)
(lambda (entry) string->list))
(if (predicate entry) (repeat entry 2) '()))
list))) (define (solve-all lines) (sum ((map solve-line) lines)))
(define (solve-line line)
((lambda (first-last-result)
(string->number (list->string first-last-result)))
(first-last is-numeric-char (string->list line))))
(define (solve-all lines)
(sum (map solve-line lines)))
(display (solve-all (read-lines))) (display (solve-all (read-lines)))

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