public static RWS <MonoidW, R, W, S, bool> Exists <MonoidW, R, W, S, A>(this RWS <MonoidW, R, W, S, A> self, Func <A, bool> pred)
where MonoidW : struct, Monoid <W> => (env, state) =>
{
var res = self(env, state);
return(res.IsFaulted
? RWSResult <MonoidW, R, W, S, bool> .New(res.Output, state, false)
: RWSResult <MonoidW, R, W, S, bool> .New(res.Output, res.State, pred(res.Value)));
};
public static RWS <MonoidW, R, W, S, int> Count <MonoidW, R, W, S, A>(this RWS <MonoidW, R, W, S, A> self)
where MonoidW : struct, Monoid <W> => (env, state) =>
{
var res = self(env, state);
return(res.IsFaulted
? RWSResult <MonoidW, R, W, S, int> .New(res.Output, state, res.Error)
: RWSResult <MonoidW, R, W, S, int> .New(res.Output, res.State, 1));
};
public static RWS <MonoidW, R, W, S, R> Fold <MonoidW, R, W, S, A>(this RWS <MonoidW, R, W, S, A> self, Func <R, A, R> f)
where MonoidW : struct, Monoid <W> => (env, state) =>
{
var res = self(env, state);
return(res.IsFaulted
? RWSResult <MonoidW, R, W, S, R> .New(res.Output, state, res.Error)
: RWSResult <MonoidW, R, W, S, R> .New(res.Output, res.State, f(env, res.Value)));
};
/// <summary>
/// Runs the RWS monad and memoizes the result in a TryOption monad. Use
/// Match, IfSucc, IfNone, etc to extract.
/// </summary>
public static RWSResult <MonoidW, R, W, S, A> Run <MonoidW, R, W, S, A>(this RWS <MonoidW, R, W, S, A> self, R env, S state)
where MonoidW : struct, Monoid <W>
{
if (self == null)
{
throw new ArgumentNullException(nameof(self));
}
if (state == null)
{
throw new ArgumentNullException(nameof(state));
}
try
{
return(self(env, state));
}
catch (Exception e)
{
return(RWSResult <MonoidW, R, W, S, A> .New(state, Error.New(e)));
}
}
public RWS <MonoidW, R, W, S, R> Ask() => (env, state) => RWSResult <MonoidW, R, W, S, R> .New(default(MonoidW).Empty(), state, env);
public static RWS <MonoidW, R, W, S, Unit> Modify <MonoidW, R, W, S, A>(RWS <MonoidW, R, W, S, A> self, Func <S, S> f)
where MonoidW : struct, Monoid <W> => (env, state) =>
RWSResult <MonoidW, R, W, S, Unit> .New(default(MonoidW).Empty(), f(state), unit);