Jonathan Blow

as soon as it exists. You're telling me I can't rough-draft or storyboard, instead I should be trying to draw finished cels of my animated movie from day one. The cost of changes is very high, so I won't end up changing very much, and I can't iterate the structure of the whole

solution without tremendous cost, so I won't do it. But I'll think I am being a Good Programmer because on the surface I am being very robust about making sure this API works, and these implementations work. The probelm is, it's the wrong API and wrong implementations.

This is also how I feel about languages that I think are "too static" like Rust. If I am just rough-drafting, I don't care if things are quite correct. Let me leak memory right now, it doesn't matter, I will probably throw away this procedure 4 times anyway; when I get to the

5th and final one, *then* let's make sure it doesn't leak memory. If you force me to be too correct up front, you remove the possibility of low-cost experimentation.

I think that software quality today is very poor, and correctness-proving systems are key to fixing this. I think the idea that Rust has that you should have annotations in your program, that ensure whatever dimensions of correctness are possible to ensure, is a good one.

But the flaw in Rust's approach is that I am forced to do this from day one (and forced to pay for it with time on every compilation). Let me experiment, let me gain expertise in this domain, then when it's time to get serious, let me layer in these checks.

(In theory you can mark an entire Rust program 'unsafe' and slowly remove this over time, but the language doesn't seem to really want you to do this, and the all-or-nothing mechanics are impractical. Let me layer in one check at a time, build it up.)

I don't mean to only address Rust here, it's just a concrete example of this class of languages. If you let me iterate and experiment, but then also provide me tools with which to ensure my program is correct, but I don't have to pay the costs of this on day one, that's great.