You should really screen capture yourself coding sometime. On a large codebase you're lucky if the compiler even runs in 10 seconds.
> Why would it be in a completely different part of the code? At most it would be 2 lines away, but usually on the same line.
Because possibly you return the partial assuming it's a number, and try to use it somewhere else, possibly even in another file.
Sorry, I must've been more explicit instead of implying certain usage patterns. What I meant here is that I have a hard time imagining this happening because I would start working on a function by writing its type signature. Unless my types check out, I won't be able to mark this function as "done" and jump to another part of code. So the situation "you return the partial assuming it's a number" simply can not happen, that's exactly what type checking is for. By the time I use it in another place, it has to already have been type checked.
I think writing out type signatures is The Right Way, but it does take time, and The Right Way doesn't always happen on complicated projects with close deadlines.