DIP 1017--Add Bottom Type--Final Review

[Walter Bright]

On 1/15/2019 8:16 PM, aliak wrote:
> +1 for not using "bottom". It's really confusing to anyone who is not a language 
> theory expert.

Fortunately, "bottom type" is very google-able, and this comes up:

https://en.wikipedia.org/wiki/Bottom_type

 > "Never" makes a lot more sense.

Inventing new jargon for established terms is worse. Established jargon gives 
the reader a certain level of confidence when established terms are used 
correctly in that the reader understands the text and that the writer 
understands the text.

The "Bottom" type appears in books on type theory, like "Types and Programming 
Languages" by Pierce. "Never" does not, leaving the reader wondering what 
relation it might have to a bottom type.

---

It reminds me of when we were coming up with a term for what became "immutable" 
types. People would say:

Q: what does 'readonly' actually mean?
A: readonly means immutable
Q: ok, I get it

Q: what does 'invariant' actually mean?
A: invariant means immutable
Q: ok, I get it

Finally we realized we were being clubbed with a Clue-By-4. Just call it 
"immutable" and voila, haven't had comprehensibility problems with it since.