but if you can avoid it I find working with type classes safer and more constrained

I think the problem is, people are not going to want to do TypeClass.apply { tests here } every time they use a matcher.

true, that's why we are proposing the Keep to have the syntax available implicitly. But in whatever case they don't have to if the Test or block surrounding the matchers has it in scope or is of that type

Yeah, but I don't know how it would be in scope other than by doing apply on a show instance. If in a test you are doing something like

val file = File(...)
file.isDirectory() shouldBe true

Then I'd like a Show<File> to be used rather than toString().

if your test class or surrounding scope implements

Show<File>

via

by

delegation it would but it's not as confortable as direct syntax, I get it