ByKey <TKey, TValue>(TKey key)
{
return
(Lens.Create <IImmutableDictionary <TKey, TValue>, TValue>(
dictionary => dictionary[key],
value => dictionary => dictionary.SetItem(key, value)));
}
Location <TValue>(int x, int y)
{
return(Lens
.Create <IImmutableGrid <TValue>, TValue>(
grid => grid[x, y],
value => grid => grid.Set(x, y, value)));
}
Lookup <TKey, TValue>(TKey key, Func <TKey, TValue> defaultFactory)
{
return
(Lens.Create <IImmutableDictionary <TKey, TValue>, TValue>(
dictionary => dictionary.Lookup(key).OrElse(defaultFactory(key)),
// ReSharper disable once ImplicitlyCapturedClosure
value => dictionary => dictionary.SetItem(key, value)));
}
Lookup <TKey, TValue>(TKey key)
{
return
(Lens.Create <IImmutableDictionary <TKey, TValue>, IMaybe <TValue> >(
dictionary => dictionary.Lookup(key),
value => dictionary =>
{
return value
.Select(x => dictionary.SetItem(key, x))
.OrElse(() => dictionary.Remove(key));
}));
}