API Docs: hash

[steveklabnik]

Part of #29329

http://doc.rust-lang.org/std/hash/

Here's what needs to be done to close out this issue:

• BuildHasherDefault needs a stronger summary/explanation distinction. "This structure is zero-sized and does not need construction." is weird.
• BuildHasher also needs a stronger summary/explanation distinction. It also needs a better explanation of why it exists with an example.
• Hash needs general improvement, it is the main bit of this module, but its docs feel tossed together and have few examples or coherence.
• Hasher needs more than just a summary line; it needs explanation and examples.

[adrianbrink]

What kind of further documentation are you looking for here? @steveklabnik

[steveklabnik]

Better explanations for https://doc.rust-lang.org/std/hash/struct.BuildHasherDefault.html

examples of implementing https://doc.rust-lang.org/std/hash/trait.BuildHasher.html and https://doc.rust-lang.org/std/hash/trait.Hash.html and https://doc.rust-lang.org/std/hash/trait.Hasher.html and more docs generally for all three.

[piordanov]

There seem to be a lengthy example of BuildHasherDefault added in this commit (d409fc3)

Also for BuildHasher and Hash.html there is a healthy amount of documentation as of now. Hasher seems to be really outdated (still lists several Implementors without mentioning they have been deprecated), which I'm looking into right now.

[brson]

Thanks @piordanov ! Looks like all that's left is documenting Hasher.

[steveklabnik]

I am happy to mentor anyone who wants to tackle this issue.

[adrianbrink]

@steveklabnik I volunteer as a tribute :-)

[steveklabnik]

@adrianbrink wonderful! If you need any help, please just let me know, as I said above, happy to help you help me 😄 (We can do it here or ping me on IRC)

[steveklabnik]

@adrianbrink I have added more specifics in the main issue above