public void SelectBothCompositionLawHolds(IEither <string, int> e)
{
bool f(int x) => x % 2 == 0;
int g(string s) => s.Length;
char h(bool b) => b ? 'T' : 'F';
bool i(int x) => x % 2 == 0;
Assert.Equal(
e.SelectBoth(x => f(g(x)), y => h(i(y))),
e.SelectBoth(g, i).SelectBoth(f, h));
}
public void ConsistencyLawHolds(IEither <string, int> e)
{
bool f(string s) => string.IsNullOrWhiteSpace(s);
DateTime g(int i) => new DateTime(i);
Assert.Equal(e.SelectBoth(f, g), e.SelectRight(g).SelectLeft(f));
Assert.Equal(
e.SelectLeft(f).SelectRight(g),
e.SelectRight(g).SelectLeft(f));
}
public static IEither <L, R1> SelectRight <L, R, R1>(
this IEither <L, R> source,
Func <R, R1> selector)
{
return(source.SelectBoth(l => l, selector));
}
public static IEither <L1, R> SelectLeft <L, L1, R>(
this IEither <L, R> source,
Func <L, L1> selector)
{
return(source.SelectBoth(selector, r => r));
}
public void SelectBothObeysIdentityLaw(IEither <string, int> e)
{
Assert.Equal(e, e.SelectBoth(Id, Id));
}