public static WriterResult <W, A> Tell <W, A>(A a, IEnumerable <W> ws)
{
if (ws == null)
{
throw new ArgumentNullException("ws");
}
return(WriterResult.Create <W, A>(a, ws));
}
/// <summary>
/// Select
/// </summary>
public static Writer <W, U> Select <W, T, U>(this Writer <W, T> self, Func <T, U> select)
{
if (select == null)
{
throw new ArgumentNullException("select");
}
return(() =>
{
var resT = self();
var resU = select(resT.Value);
return WriterResult.Create <W, U>(resU, resT.Output);
});
}
/// <summary>
/// Select Many
/// </summary>
public static Writer <W, V> SelectMany <W, T, U, V>(
this Writer <W, T> self,
Func <T, Writer <W, U> > bind,
Func <T, U, V> project
)
{
if (bind == null)
{
throw new ArgumentNullException("bind");
}
if (project == null)
{
throw new ArgumentNullException("project");
}
return(() =>
{
var resT = self();
var resU = bind(resT.Value).Invoke();
var resV = project(resT.Value, resU.Value);
return WriterResult.Create <W, V>(resV, resT.Output.Concat(resU.Output));
});
}
public static Writer <W, Unit> Tell <W>(W value)
{
return(() => WriterResult.Create <W, Unit>(Unit.Default, new W[1] {
value
}));
}
public static WriterResult <W, A> Tell <W, A>(A a, W w)
{
return(WriterResult.Create <W, A>(a, new W[1] {
w
}));
}
public static Writer <W, A> Return <W, A>(A a)
{
return(() => WriterResult.Create <W, A>(a, new W[0]));
}