Runtime error with arrays

[ckoster22]

Copy/paste into http://elm-lang.org/try

import Array exposing (Array)

type alias Box =
  { value : String }

convertTo2D : Array Box -> Int -> Array (Array Box)
convertTo2D boxArray numRows =
  let
    nextRow = Array.slice 0 numRows boxArray
  in
    if Array.length nextRow > 0
    then Array.push nextRow (convertTo2D (Array.slice numRows (Array.length boxArray) boxArray) numRows)
    else Array.empty

oneDimArray = Array.initialize 100 (\index -> { value = toString index })

temp = convertTo2D oneDimArray 10

This is boiled down from a larger application. The relevant error is:
"Uncaught TypeError: Cannot read property 'height' of undefined everything.js:831"

[jvoigtlaender]

Did you check it's not one of these existing issues about arrays?

[jvoigtlaender]

Did you check it's not one of these existing issues about arrays?

[ckoster22]

I checked. It could possibly be this issue (https://github.com/elm-lang/core/issues/349) but it's unclear whether it's the same. None of them mention the same runtime error.

[ckoster22]

I checked. It could possibly be this issue (https://github.com/elm-lang/core/issues/349) but it's unclear whether it's the same. None of them mention the same runtime error.

[jvoigtlaender]

Thanks!

[jvoigtlaender]

Thanks!

[jvoigtlaender]

I've played a bit with your example. By unrolling the recursion a bit (repeatedly inlining convert2D) and trying with reduced overall size, I reduced it to this:

import Array

temp = 
  let
    n = 10
  in 
    Array.initialize (4*n) identity
    |> Array.slice n (4*n)
    |> Array.slice n (3*n)
    |> Array.slice n (2*n)
    |> Array.slice n n

This shows the same error.

And interestingly, changing n = 10 to n = 8 lets the error go away (while it remains for n = 9). Noticing that for n = 8 we have 4*n = 32, the "magic number" from #349, it might have something to do with that issue after all, or maybe share a common root problem with that one...

[jvoigtlaender]

I've played a bit with your example. By unrolling the recursion a bit (repeatedly inlining convert2D) and trying with reduced overall size, I reduced it to this:

import Array

temp = 
  let
    n = 10
  in 
    Array.initialize (4*n) identity
    |> Array.slice n (4*n)
    |> Array.slice n (3*n)
    |> Array.slice n (2*n)
    |> Array.slice n n

This shows the same error.

And interestingly, changing n = 10 to n = 8 lets the error go away (while it remains for n = 9). Noticing that for n = 8 we have 4*n = 32, the "magic number" from #349, it might have something to do with that issue after all, or maybe share a common root problem with that one...

[evancz]

Closing in favor of #649 which will track all array issues and progress on a new implementation.

[evancz]

Closing in favor of #649 which will track all array issues and progress on a new implementation.

[wishfoundry]

I suspect this line is the culprit:

var slot = new createNode(a.height - 1, 0);

in:
https://github.com/elm-lang/core/blob/master/src/Native/Array.js#L730

createNode() generates an new node, it should not be new'ed up itself

[wishfoundry]

I suspect this line is the culprit:

var slot = new createNode(a.height - 1, 0);

in:
https://github.com/elm-lang/core/blob/master/src/Native/Array.js#L730

createNode() generates an new node, it should not be new'ed up itself