Ex: 1.51 in Cryptol Textbook

[manleykm]

When I follow this exercise, saving the file with the function

twoPlusXY (x, y) = 2 + xy
    where xy = x * y

I get the type twoPlusXY : {a} (Ring a, Literal 2 a) => (a, a) -> a. However, the book says that I should be getting the type twoPlusXY : {a} (a >= 2, fin a) => ([a],[a]) -> [a]. I was told that this might be a change in Cryptol from 2.8 to 2.9.

[manleykm]

Also, Exercise 1.54 asks "What is the value of all f [] for an arbitrary function f? Is this reasonable?". But the answer key gives the value of "any f []", changing the result from True to False.

[manleykm]

Actually, it looks like the answers to 1.54 and 1.55 were just mixed up a little.

1.54 asks about "all f []", but gives the answer to "any f []".
1.55 asks about "any f []", but mentions "If we pass all an empty sequence, then we will always get False" (where it should be saying "If we pass any an empty sequence, then we will always get False").