Yuri & Gareth

yuri_gareth/script.py

@@ -0,0 +1,112 @@
+# A token type used for just being Nil
+class Nil: # None
+    def IsNil(self):
+        return True
+
+class listOf:
+    def __init__(self, elem, rest):
+        self.head = elem
+        self.tail = rest
+
+    def IsNil(self):
+        return False
+
+    def Head(self):
+        return self.head
+
+    def Tail(self):
+        return self.tail
+
+def Cons(elem, rest):
+    return listOf(elem, rest)
+
+def Sum(a_list):
+    return foldr(int.__add__, 0, a_list)
+
+def product(a_list):
+    return foldr(int.__mul__, 1, a_list)
+
+def foldr(opr, initValue, a_list):
+    # print("foldr")
+    # if a_list.IsNil():
+    #     print(f"return {initValue}")
+    #     return initValue
+    # val = foldr(opr, initValue, a_list.Tail())
+    # head = a_list.Head()
+    # res = opr(head, val)
+    # print(f"{head} {opr} {val} == {res}")
+    # return res
+   return initValue if a_list.IsNil() else opr(a_list.Head(), foldr(opr, initValue, a_list.Tail()))
+
+
+def buildList(l):
+    return Nil() if not l else Cons(l[0], buildList(l[1:]))
+
+def AnyTrue(a_list):
+    return foldr(bool.__or__, False, a_list)
+
+def AllTrue(a_list):
+    return foldr(bool.__and__, True, a_list)
+
+def copy(a_list):
+    return foldr(Cons, Nil(), a_list)
+
+def append(a_list, b_list):
+    return foldr(Cons, copy(b_list), a_list)
+
+def length(a_list):
+    return foldr(lambda _,count_so_far: count_so_far + 1, 0, a_list)
+
+def Map(func, a_list):
+    return foldr(lambda a, b: Cons(func(a), b), Nil(), a_list)
+
+def DoubleAll(a_list):
+    double = lambda x: x*2
+    return Map(double, a_list)
+
+myEmptyList = Nil()
+print(type(myEmptyList))
+
+l1 = Cons(1, Cons(2, Cons(3, Nil())))
+print(type(l1))
+
+
+# myList = Cons(13, Cons(27, Cons(3, Nil())))
+myList = buildList([13,27,3])
+print(myList.IsNil())  # False
+print(myList.Head()) # 13
+print(myList.Tail().Head()) # 27
+
+print(Sum(myList))
+print(foldr(int.__add__, 0, myList))
+print(product(myList))
+print(foldr(int.__mul__, 1, myList))
+
+
+
+
+l = buildList([1,2,3])
+
+print(AnyTrue(buildList([False, False, True])))
+print(AnyTrue(buildList([False, False, False])))
+print(AnyTrue(buildList([])))
+
+
+print(AllTrue(buildList([True, True, True])))
+print(AllTrue(buildList([False, False, True])))
+print(AllTrue(buildList([])))
+
+
+print("------")
+print(product(myList))
+list_copy = copy(myList)
+print(myList is not list_copy)
+print(Sum(append(buildList([1,2]), buildList([3,4]))))
+
+
+
+print(length(buildList([1,2,3,4,5,6])))
+
+print("------")
+print(Sum(buildList([1,2,3,4,5,6])))
+print(Sum(DoubleAll(buildList([1,2,3,4,5,6]))))