public static TMonad Sequence <TMonad, TA>(IEnumerable <IMonad <TA> > ms)
where TMonad : IMonad <IEnumerable <TA> >
{
var monadAdapter = MonadAdapterRegistry.Get(typeof(TMonad));
var z = monadAdapter.Return(MonadHelpers.Nil <TA>());
return((TMonad)ms.FoldRight(
z, (m, mtick) => monadAdapter.Bind(
m, x => monadAdapter.Bind(
mtick, xs => monadAdapter.Return(MonadHelpers.Cons(x, xs))))));
}
public static TMonad FilterM <TMonad, TA>(Func <TA, IMonad <bool> > p, IEnumerable <TA> @as)
where TMonad : IMonad <IEnumerable <TA> >
{
var monadAdapter = MonadAdapterRegistry.Get(typeof(TMonad));
return((TMonad)@as.HeadAndTail().Match(
tuple =>
{
var x = tuple.Item1;
var xs = tuple.Item2;
return monadAdapter.Bind(
p(x), flg => monadAdapter.Bind(
FilterM <TMonad, TA>(p, xs),
ys => monadAdapter.Return(flg ? MonadHelpers.Cons(x, ys) : ys)));
},
() => monadAdapter.Return(MonadHelpers.Nil <TA>())));
}
public IEnumerable <TA> ToEnumerable()
{
return(Match(MonadHelpers.One, () => MonadHelpers.Nil <TA>()));
}