formatter aggressively reformats externs into a mess

background: https://forum.rescript-lang.org/t/my-main-gripes-with-rescript-constructive-criticism/6981/5

right now, the formatter is ruthless in formatting. this is usually appreciated, but for externs, it becomes messy sometimes.

imagine a file such as

@module("moduleX") external f1: someType1 => someType2 = "someFunc"

@module("moduleX") external f2: anotherType1 => thirdType = "someOtherFunc"

@module("moduleX") external f3: interestingType1 => interestingType2 = "someFuncWithALongerName"

@module("moduleX") external f4: t1 => t2 = "anotherFunc"

the formatter reformats it to:

@module("moduleX") external f1: someType1 => someType2 = "someFunc"

@module("moduleX") external f2: anotherType1 => thirdType = "someOtherFunc"

@module("moduleX")
external f3: interestingType1 => interestingType2 = "someFuncWithALongerName"

@module("moduleX") external f4: t1 => t2 = "anotherFunc"

because of the different lengths. this makes the externs really difficult to parse easily by looking at them because there are often repetitions and variants in the functions, so keeping them all on the same format is easier despite some lines being a little longer than what the formatter prefers.

let's discuss potential solutions for this.

Inizia dal comportamento del formatter e dagli esempi di extern in questo issue, poi leggi la discussione sul forum collegata riguardo alle soluzioni proposte e ai relativi compromessi. Done non è ancora definito: l’issue necessita di una regola di formattazione concordata prima che un nuovo contributore possa identificare il punto di ingresso dell’implementazione o i criteri di validazione.