Really? To me this is an odd claim. The planned Elixir typesystem specifically intends to build on guards as type assertions. Additionally, type assertion in a guard is de-facto useful to help code fail early on unexpected input.
I’d go so far as to say that guards semantically are pattern matches. They offer programmable extension to patterns.
We must be talking at crossed purposes, because I’d say that OTP is pretty much the embodiment of defensive programming.
I think these are the same thing: if you hit a condition for which there is no matching pattern to branch to, you have failed some invariant. In other words, you are using patterns to ensure that data flowing through your functions conform to some expected pattern. We rely on this for fast and efficient failure on unexpected data.
Yeah, I definitely agree with this. But I’d also 100% prefer a pattern match error near some unexpected data over some obscure key :whatever not found in: nil waaay down in the stack.
