Closed brandon-leapyear closed 3 years ago
I don't consider this a bug. I wonder if we should keep this open.
:sparkles: This is an old work account. Please reference @brandonchinn178 for all future communication :sparkles:
Sure, this could be considered a feature request. I think this is a worthwhile issue, though, because (- x)
very much looks like a partial section, not a unary operator
But (-x)
and (- x)
are parsed as identical constructs on the AST level, right?
:sparkles: This is an old work account. Please reference @brandonchinn178 for all future communication :sparkles:
Yes, but the point of a formatter is to enforce consistent style for the sake of readability across a codebase. IMO, (- x)
is much less readable than (-x)
, and the formatter should style in the more readable format
:sparkles: This is an old work account. Please reference @brandonchinn178 for all future communication :sparkles:
Adding on to this,
f n = n-1
gets reformatted to
f n = n -1
Distinguishing between negation operator and minus would be nice
The reason why ormolu adds spaces after -
is due to #181: NegativeLiterals
is not part of manualExts
, so the expressions -1
and - 1
as parsed via ormolu without further options have differing ASTs (the literal -1
and the negated literal 1
). Without NegativeLiterals
, they would have the same AST. In all other places, the space after the -
is not necessary.
In #734, I added NegativeLiterals
to manualExts
, and only add a space after -
if we negate a literal and NegativeLiterals
is actually enabled.
This means that
f x = 1 / (1 + exp (-x))
is a fixed point, and
f n = n-1
is formatted into
f n = n - 1
As a side note: GHC 9.0 added the new extension LexicalNegation
which allows (- x)
to be an operator section, such that
{-# LANGUAGE LexicalNegation #-}
add2AndSubtract3 :: Bifunctor f => f Int Int -> f Int Int
add2AndSubtract3 = bimap (+ 2) (- 3)
is a fixed point, and add2AndSubtract3 (1,2) == (3,-1)
. Without LexicalNegation
, the code would be formatted to
add2AndSubtract3 :: Bifunctor f => f Int Int -> f Int Int
add2AndSubtract3 = bimap (+ 2) (-3)
which makes it easy to spot that something is wrong.
Describe the bug
To Reproduce
gets reformatted as
Apparently GHC still treats this as equivalent, but it's very easy to mistakenly read it as a partially applied
-
Expected behavior
(-x)
should kept as(-x)
Environment
Additional context Add any other context about the problem here.