[stdlib] Use type inference for Bool vars

[jawwad]

This commit makes the declarations of boolean variables more concise by using type inference

[CodaFi]

It may be concise, but I always appreciate when type annotations are kept around, even in simple cases like this.

[liambutler-lawrence]

+1 on this. In my opinion, type annotations can be useful when the type is unclear from a quick glance (for example, when assigning the result of a long function chain). In this case, however, we're clearly assigning a Boolean literal (either "true" or "false") to each variable. Explicitly writing “: Bool” only makes the declaration longer and less instantly readable.

[jawwad]

While I do prefer always using type inference, I can appreciate how others including @CodaFi would prefer that they be kept around so this change may be more subjective than I thought. And perhaps a bit more in the case of instance variables where other variables without initial default values have types specified. Curious to hear what others have to say on this, and if Apple has any kind of recommendation on minor style concerns like this.

[gribozavr]

@jawwad Some of the library code will be fragile, and having explicit type annotations will help to not accidentally break ABI. We prefer to postpone this discussion until resilience is implemented and applied to the library.