HoistState <TState, TValue>(
StateCxt <TState> _cxt,
Maybe <TValue> value)
{
var m = new MaybeT <State <TState, TValue>, State <TState, Maybe <TValue> >, Maybe <TValue>, TValue>();
return((MaybeT <State <TState, TValue>, State <TState, Maybe <TValue> >, Maybe <TValue>, TValue>)m.Hoist(value));
}
public static void LinqStateTest()
{
var cxt = new StateCxt <string>();
var computation =
from x in MaybeT.Lift(cxt.Get())
from y in MaybeT.Lift(cxt.Put("xyz"))
from z in MaybeT.Lift(cxt.Modify(s => x + "___"))
from u in MaybeT.Lift(cxt.Get())
from _ in MaybeT.HoistState(cxt, Maybe.JustIf(x.Length >= 3, () => 1))
from v in MaybeT.Lift(cxt.Put("gef"))
select u;
var(value, state) = computation.Run.Run("abc");
Assert.True(value.HasValue);
Assert.Equal("abc___", value.Value());
Assert.Equal("gef", state);
(value, state) = computation.Run.Run("ab");
Assert.False(value.HasValue);
Assert.Equal("ab___", state);
}