import copy import sys import random def cons(x, l): new_l = copy.copy(l) new_l.insert(0,x) return new_l def head...

import copy

import sys

import random

def cons(x, l):

new_l = copy.copy(l)

new_l.insert(0,x)

return new_l

def head (l):

if l == []:

print("Cannot call head on the empty list.", file=sys.stderr)

sys.exit()

x , *xs = l

return x

def tail (l):

if l == []: return []

x, *xs = l

return xs

def append(l1,l2):

return l1 + l2

def reverse(l):

new_l = copy.copy(l)

new_l.reverse()

return new_l

def repeat(x,n):

if n 0:

print ("Cannot call repeat with negative values.", file=sys.stderr)

sys.exit()

return [x] * n

def _take(n,acc,l):

if n == 0:

return acc

elif n 0:

print ("Cannot call take with negagive values.", file=sys.stderr)

sys.exit()

x = head(l)

rest = tail(l)

return _take (n-1,cons(x,acc),rest)

def take(n,l):

if l == []: return []

return reverse (_take(n,[],l))

def drop(n,l):

if n == 0:

return l

elif n 0:

print ("Cannot call drop with negative values.", file=sys.stderr)

sys.exit()

es = tail (l)

return drop (n-1, es)

def _length(acc, l):

if l == []:

return acc

return _length(1+acc,tail(l))

def length(l):

return _length(0,l)

def _randint_list(n, acc, low, high):

if n == 0: return acc

x = random.randint(low,high)

return _randint_list (n - 1, cons(x,acc), low, high)

def randint_list(n, low, high):

if n 0:

print ("Cannot call randint_list with negative values.", file=sys.stderr)

sys.exit()

return _randint_list(n,[], low, high)

def _randfloat_list(n, acc, low, high):

if n == 0: return acc

x = random.randint(low,high)

return _randfloat_list (n - 1, cons(x,acc), low, high )

def randfloat_list(n, low, high):

if n 0:

print ("Cannot call randint_list with negative values.", file=sys.stderr)

sys.exit()

return _randfloat_list(n,[], low, high)

def unique(l):

if l == []:

return []

e = head (l)

es = tail (l)

new_tail = [x for x in es if x != e]

return cons(e, unique(new_tail))

def list_range(low, high):

return list(range(low, high))