StrMap fromFoldable stack explosion

[matthewleon]

try

M.fromFoldable $ (flip Tuple) unit <<< show <$> L.range 0 9999

This works.

Now add a 9. Boom.

Data.Map maps work fine with this.

[natefaubion]

It uses for_ which is not stack-safe. An alternative would be to fold into an Array first, and use foreachE.

[matthewleon]

It uses for_ which is not stack-safe. An alternative would be to fold into an Array first, and use foreachE.

A rock and a hard place. Is there no balm in Gilead?

[matthewleon]

More seriously, I feel like there has to be a better way to fix this than generating a big pile of garbage to collect. But maybe I am very wrong.

[natefaubion]

You can also use unsafe effects with foldl/foldr.

[matthewleon]

You can also use unsafe effects with foldl/foldr.

That's like using the cheat code and saying you beat the game, though, isn't it? :)

To be fair... I guess Data.Array goes well beyond this.

[hdgarrood]

Should this be considered a bug in the Traversable List instance?

[matthewleon]

Should this be considered a bug in the Traversable List instance?

I would say so. I'm having a look at what can be done there.

[natefaubion]

Should this be considered a bug in the Traversable List instance?

for_ is only Foldable in any case. The stack-unsafety is in the sequencing of Applicative effects.

[natefaubion]

That's like using the cheat code and saying you beat the game, though, isn't it? :)

You may only use foldl/foldr, but then you generate garbage by copying StrMaps. If you want to use mutation, you must sequence effects, which is not necessarily stack safe. To guarantee that, you must use MonadRec (ala purescript-safely), which has it's own overhead. Pick two: purity, stack-safety, effeciency.

[matthewleon]

Pick two: purity, stack-safety, effeciency.

[natefaubion]

You can also wait until proper tail-calls are implemented pervasively, and the problem will probably take care of itself.

[matthewleon]

You can also wait until proper tail-calls are implemented pervasively

Is there an issue for this one? Did a search and couldn't find it.

[natefaubion]

I was referring to tail-call support in JS engines :)

[matthewleon]

I was referring to tail-call support in JS engines :)

Ah yes, indeed. How will that help with foldr though?

[michaelficarra]

Unfortunately, Safari and V8-behind-a-flag will be the only implementations for a while. Edge has inherent call stack design limitations which prevent it and Firefox has inherent security design limitations which prevent it.

[hdgarrood]

Was this fixed by #110?

[natefaubion]

Yes.