Formatter Breaks Explicit Partial Application Syntax When Split By a Line Break

[LTibbetts]

The formatter is applying a trialing comma to the new explicit partial application function syntax which breaks compilation of otherwise compiling code. This only seems to happen when the line length is long enough to force a line break from the formatter.

Unformatted (Compiles)

module LongModuleName = {
  let functionWithAlongNameThatWrapsTheEditorToTheNextLine = (a: int): int =>
    a * 3 + 2
}

let mapWithAReallyLongName = (f: 'a => 'b, a: 'a) => {
  f(a)
}

let functionThatTakesThing =
  mapWithAReallyLongName(
    a => LongModuleName.functionWithAlongNameThatWrapsTheEditorToTheNextLine(a),
    ...
  )

let b = functionThatTakesThing(1)

Formatted (Syntax Error)

module LongModuleName = {
  let functionWithAlongNameThatWrapsTheEditorToTheNextLine = (a: int): int =>
    a * 3 + 2
}

let mapWithAReallyLongName = (f: 'a => 'b, a: 'a) => {
  f(a)
}

let functionThatTakesThing =
  mapWithAReallyLongName(
    a => LongModuleName.functionWithAlongNameThatWrapsTheEditorToTheNextLine(a),
-    ...
+    ...,
  )

let b = functionThatTakesThing(1)