[m-rev.] for review: structured types in error messages

[Zoltan Somogyi]

2022-02-21 11:59 GMT+11:00 "Peter Wang" <novalazy at gmail.com>:
>> +            ArgPiecesList = [ReturnValuePieces],
>> +            PorFArgBlockPieces = [fixed("func"), fixed("=")] ++
>>                  FuncResultPrefixPieces ++ ReturnValuePieces ++
>>                  FuncResultSuffixPieces
> 
> "(func)" instead of "func".

Function declarations without arguments do not need
parentheses, as shown by e.g.

:- func max_one_line_type_length = int.

Function types without arguments do need parentheses
when inside bigger types.

Therefore I see three options:

- Always add parentheses, which is misleading
  if the function type is the outermost type.

- Never add parentheses, which is (readable, but)
  misleading about the need for parentheses
  if the function type is not the outermost type.

- Pass along a flag that says whether the type is
  the outermost or not, and add parentheses
  only if it is not.

I would prefer the third. Do you object?

> The rest looks fine.

Thank you.

Zoltan.