/// <summary>
/// (<$)
/// <para>a = TResult, b = TSource</para>
/// <para>Create a new f a from an f b by replacing all of the values in
/// the f b by a given value of type a.</para>
/// </summary>
public static Mayhap <TResult> ReplaceWith <TSource, TResult>(
TResult value,
Mayhap <TSource> mayhap)
where TResult : notnull
{
// (<$) :: Functor f => a -> f b -> f a | infixl 4 |
//
// (<$) :: a -> f b -> f a
// (<$) = fmap . const
//
// Replace all locations in the input with the same value. The
// default definition is fmap . const, but this may be overridden
// with a more efficient version.
//
// Examples:
// "xxx" <$ Nothing == Nothing
// "xxx" <$ Just 1 == Just "xxx"
#if STRICT_HASKELL
return(Map(__const, mayhap));
// NB: this is just (_ => value).
TResult __const(TSource x) => Thunks <TResult, TSource> .Const1(value, x);
#else
return(mayhap.Select(_ => value));
#endif
}
// First law: the identity map is a fixed point for Select.
// fmap id == id
public static bool IdentityRule <T>(Mayhap <T> mayhap)
{
#if STRICT_HASKELL
return(Map(Thunks <T> .Ident, mayhap)
== Thunks <Mayhap <T> > .Ident(mayhap));
#else
return(mayhap.Select(Thunks <T> .Ident)
== Thunks <Mayhap <T> > .Ident(mayhap));
#endif
}
public static void Test10(ref Thunks obj)
{
obj = new Thunks();
}
