Allow undentation for constructors

[charlesroddie]

It's good to be able to move 4 characters to the right to get to the next level and leads to smart code where lines generally start at a indentation which is a multiple of 4. This works well with tooling (Tab/shift-tab).

However in constructors, full indentation is required. So when defining types, the length of the type name determines how far to the right inputs must be positioned:

open System
type SixAccessViolations(a:AccessViolationException,
                         b:AccessViolationException,
                         c:AccessViolationException,
                         d:AccessViolationException,
                         e:AccessViolationException,
                         f:AccessViolationException) =
    class end

Undentation is not allowed:

type SixAccessViolations(a:AccessViolationException,
        b:AccessViolationException, c:AccessViolationException,
        d:AccessViolationException, e:AccessViolationException,
        f:AccessViolationException) =
    class end

Function inputs allow undentation (and it's explicitly in the F# spec):

let sixAccessViolations =
    SixAccessViolations(accessViolation,
        accessViolation, accessViolation,
        accessViolation, accessViolation,
        accessViolation)

[cartermp]

I would like to see this done if possible.

[dsyme]

Marked as approved. I'll try to look at this today

[dsyme]

This suggestion is implemented in dotnet/fsharp#6314

@charlesroddie Any chance you could write up a brief RFC? @cartermp has broken his arm so can't type fast :/

[charlesroddie]

Travelling at the moment but I will give it a go in a few days.

[cartermp]

Thanks @charlesroddie

[dsyme]

@cartermp You're not meant to be typing!

[FunctionalFirst]

@dsyme Only asking because I haven't seen an example of this. Will undentation of the first input be allowed? E.g.,

type SixAccessViolations(
    a:AccessViolationException,
    ...) =

[charlesroddie]

@FunctionalFirst Yes and that will be a very common way to format. That's how it works with function inputs at the moment.

[dsyme]

@dsyme Only asking because I haven't seen an example of this. Will undentation of the first input be allowed?

We should double check - the test cases in the PR doesn't cover this yet https://github.com/Microsoft/visualfsharp/pull/6314/files#diff-d652333102a65f9f23289cb1d40938bbR249

[charlesroddie]

@dsyme Sorry: I didn't have enough time/internet/power to look at the RFC while I was away.

This proposal was for constructors, which tend to have a lot of inputs and long names.
You added static members.
What do you think about extending it to all functions?

// The proposal currently is to allow undentation in constructors and static members.
// Currently: warning FS0058: Possible incorrect indentation
// Proposed: OK
type EightCalculator(
        irrelevantNumber1:int,
        irrelevantNumber2:int) =
    member t.Eight = 8

// Should undentation in other functions be allowed too?
// Currently: warning FS0058: Possible incorrect indentation
// Proposed: OK?
let nineCalculator(
        irrelevantNumber1:int,
        irrelevantNumber2:int) =
    9

let irrelevantNumber1 = 1
let irrelevantNumber2 = 2

// OK: undentation allowed when calling constructors
let eight =
    let ec =
        EightCalculator(
            irrelevantNumber1,
            irrelevantNumber2)
    ec.Eight

// OK: ... and other functions
let nine =
    nineCalculator(
        irrelevantNumber1,
        irrelevantNumber2)

[dsyme]

Completed