Awkward error message for incompatible fixities

[brianhuffman]

For example:

cryptol> :t \a b c d -> a == b || b == c

[error]
    The fixities of (at <interactive>:1:15--1:17, (==)) and
    (at <interactive>:1:25--1:27, (==)) are not compatible.
    You may use explicit parenthesis to disambiguate

It is very weird to read a noun phrase starting with "at"; the operator is the important bit and it should come first. Also the last sentence should use plural "parentheses" and have a period.

I would prefer this:

[error]
    The fixities of (==) (at <interactive>:1:15--1:17) and
    (==) (at <interactive>:1:25--1:27) are not compatible.
    You may use explicit parentheses to disambiguate.

[brianhuffman]

Actually, it would be even better to print not just the operators, but also the fixities/precedence levels in the error message itself. Maybe something like:

[error] at <interactive>:1:15--1:17 and <interactive>:1:25--1:27
    The fixities of (==) (precedence 20, non-associative) and
    (==) (precedence 20, non-associative) are not compatible.
    You may use explicit parentheses to disambiguate.

[brianhuffman]

@yav suggested using a bulleted list to make the error message easier to read. As of eb7b74a, the error message looks like this:

Cryptol> True == False != True

[error] at <interactive>:1:6--1:8 and <interactive>:1:15--1:17
    The fixities of
      • (==) (precedence 20, non-associative)
      • (!=) (precedence 20, non-associative)
    are not compatible.
    You may use explicit parentheses to disambiguate.