def any(xs):
if not xs:
return False
else:
x = head(xs)
if x:
return True
return or_(x, any(tail(xs)))
def all(xs):
if not xs:
return True
else:
x = head(xs)
if not x:
return False
return and_(x, all(tail(xs)))
def foldr(f, v, xs):
if not xs:
return v
else:
return f(head(xs), foldr(f, v, tail(xs)))
def length(xs):
if not xs:
return 0
else:
return 1 + length(tail(xs))
def reduce(f, xs):
if not xs:
return 0
else:
return f(head(xs), reduce(f, tail(xs)))
def filter(p, xs):
if not xs:
return []
else:
return [head(xs)] + filter(p, tail(xs)) if p(head(xs)) else filter(p, tail(xs))
def map(f, xs):
if not xs:
return []
else:
return [f(head(xs))] + map(f, tail(xs))
def reverse(xs):
if not xs:
return []
else:
return reverse(tail(xs)) + [head(xs)]
def product(xs):
if not xs:
return 1
else:
return head(xs) * product(tail(xs))
def sum(xs):
if not xs:
return 0
else:
return head(xs) + sum(tail(xs))
def foldr(f, v, xs):
if not xs:
return v
else:
return f(head(xs), foldr(f, v, tail(xs)))
