The code should be self-explanatory.
The state of the game is modeled as a pair of integers (representing a range containing the number chosen by the player).
The input from the player is first modeled as a linear stream (of linear strings) and then converted to a linear stream of responses (where each response is essentially an integer).
The following function updates the state of the game based the current response from the player:
fun
stateUpdate
( s0: !state >> _
, r0: resp): void =
let
val+
@State(L, H) = s0
in
//
fold@(s0) where
{
val () =
case+ r0 of
| Okay() => ()
| Lower() => H := (L+H)/2-1
| Higher() => L := (L+H)/2+1
| Error() => ()
}
//
end // end of [stateUpdate]Note that this is a memory-clean implementation in the sense that every allocated byte is freed before the program exits. The code in this example for handling input does essentially the same as the code in ReadFromSTDIN.
Happy programming in ATS!!!