List equality

[Turgut Guneysu]

Following code blocks evaluate to false:

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[John Maloney]

This is worth thinking about. It would need to be recursive to handle lists inside of lists, and a recursive implementation would need to protect itself against circular data structures.

But perhaps a non-recursive implementation would be better than nothing. That would deal the case above and probably 95% of beginner situations. And those advanced enough to build more complex data structures could write their own recursive equality test.

[Bernat Romagosa]

Most programming languages will report false to [1, 2, 3] = [1, 2, 3], but I see the pedagogical value in that. In Snap_!_ we do have list comparison. It is recursive and it avoids circular references.

Here’s Jens' implementation in case we want to base ours on that one: https://github.com/jmoenig/Snap/blob/master/src/lists.js#L545

[Turgut Guneysu]

Here is the SNAP! version:

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[Dariusz Dorożalski]

Maybe a makeshift

[John Maloney]

Clever idea!

But inspired me to add a "list _ equals _" block to the list library that does a fully recursive list comparison. That will be in the next pilot release.

[John Maloney]

You can now use the "list _ equals _" block from the Lists library to test for list equality.