Scheme Implementation of the Filter-Map-Reduce pattern

filterMapReduce.scm

; return a new list, where elements that do not
; meet the conditions of the filter function are removed
(define myfilter
  (lambda (func lat)
    (cond
      ((null? lat) (quote ()))
      ((func (car lat)) (cons (car lat)
                              (myfilter func (cdr lat))))
    (else
      (myfilter func (cdr lat))))))

; return a new list, where each element in lat has been
; transformed by func
(define mymap
  (lambda (func lat)
    (cond
      ((null? lat) (quote ()))
    (else
      (cons (func (car lat))
            (mymap (cdr lat) func))))))
  
 
 ; reduce lat to a single value, accumulated in acc
(define myreduce
  (lambda (func lat acc)
    (cond
      ((null? lat) acc)
    (else
      (func (car lat)
            (myreduce func (cdr lat) acc))))))