Add &, |, %, and ~ operators

[potomak]

See also http://www.postgresql.org/docs/9.4/static/functions-math.html.

[meteficha]

Thanks for the PR!

• Please add | and ~ operators as well.
• Please add /Since: 2.4.2/ to the Haddocks of the new operators.

[potomak]

I'm adding | and ~. To support ~ I'm creating an helper function unsafeSqlUnOp, similar to unsafeSqlBinOp.

[potomak]

I added |, ~, and unsafeSqlUnOp. Do you think it would be fine to implement the NOT operator in terms of unsafeSqlUnOp?

[meteficha]

Hmm, the bitwise not will have to be used as (~.) foo, right? I haven't tried but I don't think ~. foo will work. Can you rename it to bitwiseNot to avoid confusion?

Yeah, implementing not_ with unsafeSqlUnOp would be fine! We'll lose the more specific error, but who's not_ing a primary key anyway? :)

[potomak]

Yes, I don't think ~. foo would work and I had the same concern about the usage as (~.) foo. The bitwiseNot function name makes more sense even if it's not consistent with all the other bitwise operators.

I will

1. rename (~.) to bitwiseNot;
2. implement not_ with unsafeSqlUnOp.