[nigeltao]

Yeah, you're right. It's not as easy to write Wuffs code during the research phase, since you don't just have to write the code, you also have to help the compiler prove that the code is safe, and sometimes refactor the code to make that tractable.

Wuffs doesn't support global variables, but when I'm writing my own research phase code, sometimes I like to just tweak some global state (without checking the code in) just to get some experimental data: hey, how do the numbers change if I disable the blahblah phase when the such-and-such condition (best evaluated in some other part of the code) holds?

Also, part of Wuffs' safety story is that Wuffs code cannot make any syscalls at all, which implies that it cannot allocate or free memory, or call printf. Wuffs is a language for writing libraries, not whole programs, and the library caller (not callee) is responsible for e.g. allocating pixel buffers. That also makes it harder to use during the research phase.