-- You could maybe equate this with an 'array'.
-- Indexed set example:
S = [ "b"; "c"; "a" ]
I = [ 0; 1; 2 ]
-- A is the "array" here
A : I -> S
A 0 = "b"
A 1 = "c"
A 2 = "a"
-- or, equivalently
A = [
(0, "b")
(1, "c")
(2, "a")
]
-- This is very cumbersome though, hence the alternate syntax
A = [| "b"; "c"; "a" |]
assert (A 1 == "c")
assert (A -< I * S) -- A is a subset of the cartesian product of I and S.
-- An indexed ste is similar to,
-- but not the same as a tuple/ordered pair.
a = ("b", "c", "d")
assert (A /= a)
assert <| all [ nth i a == A i => i <- I ]
