Improve pattern-matching

[yuri-karadzhov]

In the following pattern

{x,y:[a,b]} = {x:1,y:[2,3]}

it's expected that

x == 1, y == [2, 3], a == 2, b ==3

but y is undefined, despite _ref1 contains y

a: 2, b: 3, x: 1, _ref: { x: 1, y: [ 2, 3 ] }, _ref1: [ 2, 3 ]

[vendethiel]

Yeah, because it's only the key in the case of a deep destructuring (not "pattern match"). We'd need as-pattern - See also #363.

[yuri-karadzhov]

Is there any reason not to do deep destructure? Formaly it's not pattern-matching anyway because

{x,y:[2,b]} = {x:1,y:[2,3]}

will not work.

[vendethiel]

not to do deep destructure

We do deep destructure -- we just don't provide the intermediate objects. The comments in the issue I linked seem to indicate that a series of destructuring is the correct answer

---

Formaly it's not pattern-matching

Indeed, hence what I said :

(not "pattern match").

[yuri-karadzhov]

we just don't provide the intermediate objects

Why? What's wrong with providing intermediate objects? Of course it is possible to solve above issue this way

{_, y} = {x,y:[a,b]} = {x:1,y:[2,3]} # y = [2,3]

but what is the reason to do the same work twice and have more auxiliary variables?

The issue you linked seems to describe different question which is solved in CS

z = {x,y:[a,b]} = {x:1,y:[2,3]} # z = {x:1, y:[2,3]}