def filter_f(p):
return (
lambda list_f: Nil
if nil(list_f)
else filter_f(p)(tail(list_f))
if not p(head(list_f))
else cons(head(list_f))(filter_f(p)(tail(list_f)))
)
def eq(lst1):
return (
lambda lst2: True
if nil(lst1)
and nil(lst2)
or not nil(lst1)
and not nil(lst2)
and head(lst1) == head(lst2)
and eq(tail(lst1))(tail(lst2))
else False
)
def inner(lst):
if nil(lst):
return False
elif head(lst) == e:
return True
else:
return elem(e)(tail(lst))
def unzip_func(list_pairs):
if nil(list_pairs):
return pair(Nil)(Nil)
else:
tail_unzipped = unzip_func(tail(list_pairs))
head_pair = head(list_pairs)
return pair(cons(fst(head_pair))(fst(tail_unzipped)))(
cons(snd(head_pair))(snd(tail_unzipped))
)
def foldr(f):
return (
lambda accm: lambda list_f: accm
if nil(list_f)
else f(head(list_f))(foldr(f)(accm)(tail(list_f)))
)
def map_f(f):
return lambda list_f: Nil if nil(list_f) else cons(f(head(list_f)))(map_f(f)(tail(list_f)))
def concat(lst1):
return lambda lst2: lst2 if nil(lst1) else cons(head(lst1))(concat(tail(lst1))(lst2))
def drop(n):
return lambda lst: lst if nil(lst) or n == 0 else drop(n - 1)(tail(lst))
def take(n):
return lambda lst: Nil if nil(lst) or n == 0 else cons(head(lst))(take(n - 1)(tail(lst)))
def length(lst):
return 0 if nil(lst) else 1 + length(tail(lst))
def last(lst):
return (lambda t: head(lst) if nil(t) else last(t))(tail(lst))
def zip_f(a_lst_f):
return (
lambda b_lst_f: Nil
if nil(a_lst_f) or nil(b_lst_f)
else cons(pair(head(a_lst_f))(head(b_lst_f)))(zip_f(tail(a_lst_f))(tail(b_lst_f)))
)
def init(lst):
return (lambda t: Nil if nil(t) else cons(head(lst))(init(t)))(tail(lst))