PLQ #8

Question 1 @ 2021-03-16 18:31

Say that we’re using a(n infix) language that implements = assignments. It can be said that the expression

x = y = x

swaps the values of x and y. Given this (and that all of the expressions in our language evaluate to some value) what must an assignment expression evaluate to in our language?

a
A bogus value
b
The new value that was assigned
c
The old value (before the assignment)

Question 2 @ 2021-03-16 18:34

Say that we’re using a(n infix) language that implements = assignments. It can be said that the expression

x = y = x

swaps the values of x and y. Given this (and that all of the expressions in our language evaluate to some value) we know that assignment expressions evaluate to the old value.

What did we assume to make that conclusion?

a
The language is statically typed
b
The language is eager
c
The language is lazy
d
The language is compositional
e
The language is compiled

Question 3 @ 2021-03-16 18:37

A Mod2Digit is one of: 0, 2, 4, 6, 8
A Mod4Digit is one of: 0, 4, 8

Which of the following subtype relations hold?

(T1 ⊂ T2 means T1 is a subtype of T2; Select all that apply.)

a

(Listof MOD2Digit) ⊂ (Listof MOD4Digit)
b

(Listof MOD4Digit) ⊂ (Listof MOD2Digit)
c

T -> MOD2Digit ⊂ T -> MOD4Digit
d

T -> MOD4Digit ⊂ T -> MOD2Digit
e

MOD2Digit -> T ⊂ MOD4Digit -> T
f

MOD4Digit -> T ⊂ MOD2Digit -> T
g

(Boxof MOD2Digit) ⊂ (Boxof MOD4Digit)
h

(Boxof MOD4Digit) ⊂ (Boxof MOD2Digit)

Question 4 @ 2021-03-16 18:42

What will be the result of the following test for the with in HW10?

(->nat (with [* +]
(with [x (* 3 3)]
(with [+ *]
(+ x x)))))

a
12
b
18
c
81
d
162
e
Syntax error since we need to use {}s in Schlac
f
Some random value since all functions are curried

Question 5 @ 2021-03-16 18:46

Is the TOY language eager or lazy?

a
Eager
b
Lazy
c
Whatever the implementing language is
d
Irrelevant since it’s statically typed

Question 6 @ 2021-03-16 18:48

(test (run "{bind {{identity {fun {x} x}}
{add1 {fun {x} {+ x 1}}}}
{{identity add1} 123}}")
=> 124)

Does the above test pass in TOY?