Inconstistency with empty splat and commas

[vendethiel]

coco -bce "[..., a]=[0 1]; [..., b,]=[0 1]; a == b"
true

[satyr]

I don't see inconsistency there. Single trailing comma is simply ignored as in JS and many other languages:

$ node
> [0]
[ 0 ]
> [0,]
[ 0 ]
> [0,,]
[ 0,  ]

[michaelficarra]

Agreed.

[vendethiel]

Uh. That seems anti-natural since it's a destructuring pattern more than an array. What's the use case where you put a trailing comma at the end of a destructuring pattern ? (I never used a single one in coco/coffee/whatever)
It seems like a valid explanation tho ...

[satyr]

What's the use case where you put a trailing comma at the end of a destructuring pattern ?

When one span multiline I guess:

js> [ a,
      b,
    ] = [ 
      0,
      1,
    ]
[0, 1]

Admittedly not very useful in Coffee families since we don't need those commas at all.

[vendethiel]

My exact point.

I also find it inconsistent with array voids : [,] is [void] and [,,] is [void void]

[satyr]

In those cases the commas aren't optional, indicating empty items.

js> [,].length
1
js> [,,].length
2

coco> [,].length
1
coco> [,,].length
2

[vendethiel]

Yup, so [,,] is not consistent with [4,]

[satyr]

Comparing those two is pointless.

[,,] is short for [void, void,] and consistent with [4, 4,] etc.