ambiguous linebreaking of assignments (question)

[exaexa]

Hello!

is Runic formatting output supposed to depend on changes of blank characters in the input?

In particular I found a few spots where Runic accepts two different line-breakings as "OK" and doesn't change them (i.e., does not enforce the unique formatting), no matter that they are equivalent as source code:

x = 0

x =
    0

Is this intended? If it is, is there be some way (option perhaps) to enforce a completely blanks-insensitive formatting?

Thanks!
-mk

cc @stelmo

[exaexa]

as a note, the "line-breaked" form indentation looks particularly sub-optimal in cases; e.g. here:

    line_system =
        :point^C.ConstraintTree(
        :x => C.Constraint(0 + 2 * line_param),
        :y => C.Constraint(0 + 1 * line_param),
    )

(taken from ConstraintTrees.jl)

[exaexa]

another example (again taken plain from ConstraintTrees:)

Base.:+(a::LinearValue, b::LinearValue) =
let
    (idxs, weights) =
        add_sparse_linear_combination(a.idxs, a.weights, b.idxs, b.weights)
    LinearValue(; idxs, weights)
end

#vs.

Base.:+(a::LinearValue, b::LinearValue) = let
    (idxs, weights) = add_sparse_linear_combination(a.idxs, a.weights, b.idxs, b.weights)
    LinearValue(; idxs, weights)
end

[fredrikekre]

Hi, in general Runic doesn't modify newlines in the source. So for example, if you have put a line break after = it will still be there.

x = 0

x =
    0

as a note, the "line-breaked" form indentation looks particularly sub-optimal in cases; e.g. here [...]

Yea but doesn't it almost always look better with no newline after the =? Like

line_system = :point^C.ConstraintTree(
    :x => C.Constraint(0 + 2 * line_param),
    :y => C.Constraint(0 + 1 * line_param),
)

Base.:+(a::LinearValue, b::LinearValue) =
let
    (idxs, weights) =
        add_sparse_linear_combination(a.idxs, a.weights, b.idxs, b.weights)
    LinearValue(; idxs, weights)
end

This would again look better as function ... end or at least with the let on the same line as =. This particular case was discussed a bit in #39

[exaexa]

@fredrikekre ah I see, thanks for the explanation.

Just a few notes about the examples:

line_system =
    :point^C.ConstraintTree(
    :x => C.Constraint(0 + 2 * line_param),
    :y => C.Constraint(0 + 1 * line_param),
)

this is mildly confusing because the "point", "x" and "y" look like the same-level kind of thing, because they "share the indent"

Re the second example, full agree that it would be better with function but we got a relatively good form from JuliaFormatter (as you said, with = on the same line) so was wondering what went wrong.

The property with retained linebreaks explains it, this issue is then effectively not an issue, so closing. Thanks again! :)

[fredrikekre]

this is mildly confusing because the "point", "x" and "y" look like the same-level kind of thing,

I agree, it is tricky. This is related to the "hard" vs "soft" indenting discussed in https://github.com/fredrikekre/Runic.jl/blob/master/README.md#indentation.

Going with just "hard" indent would do

line_system =
    :point^C.ConstraintTree(
        :x => C.Constraint(0 + 2 * line_param),
        :y => C.Constraint(0 + 1 * line_param),
    )

becuase the =-expression and the call to ConstraintTree are multiline expressions. However, if you didn't have the newline after = it would become

line_system = :point^C.ConstraintTree(
    :x => C.Constraint(0 + 2 * line_param),
    :y => C.Constraint(0 + 1 * line_param),
)

so this is also a bit inconsistent.

[exaexa]

Yeah, the hard indent might be too much. The "slightly inconsistent" is mildly inconsistent w.r.t. AST (depending on how you define consistency) but at least consistent w.r.t. user-visible brackets (parentheses in this case).

Just to be complete about the design space, this is a possible middle ground taken by many formatters:

line_system = :point^C.ConstraintTree(
        :x => C.Constraint(0 + 2 * line_param),
        :y => C.Constraint(0 + 1 * line_param),
    )

[fredrikekre]

Yea, I don't mind that formatting, just isn't how most existing (Julia) code look like. For example, if I have code like this:

push!(
    x, 
    1,
    2
)

and then later want to assign the result of this call and adding y = in front of the push!. With the existing Runic implementation there wouldn't be any extra diff generated from indenting all the following lines too.