Method substitute

src/main/java/wyil/lang/WyilFile.java:6925–6945

(Tuple<Type> types,
			java.util.function.Function<Object, Syntactic.Item> binding)

	}

	private static Tuple<Type> substitute(Tuple<Type> types,
			java.util.function.Function<Object, Syntactic.Item> binding) {
		for (int i = 0; i != types.size(); ++i) {
			Type before = types.get(i);
			Type after = before.substitute(binding);
			if (before != after) {
				// Committed to change
				Type[] nTypes = new Type[types.size()];
				for (int j = 0; j != nTypes.length; ++j) {
					after = types.get(j).substitute(binding);
					if(after == null) {
						return null;
					}
					nTypes[j] = after;
				}
				return new Tuple<>(nTypes);
			}
		}
		//
		return types;
	}

	private static Type[] substitute(Type[] types, java.util.function.Function<Object, Syntactic.Item> binding) {
		Type[] nTypes = types;