readFloat and readInt should return maybes

[davidchambers]

Should these functions return values of type Maybe Number rather than Number? NaN checks, like null checks, are easy to forget.

[garyb]

I'm not sure, possibly. NaN is a valid number in PureScript (unfortunately) as there are many different ways it can creep in.

[paf31]

Maybe we could add these as alternatives. The issue is that then Globals would depend on Maybe, which I think is a little bit of a shame.

[garyb]

Perhaps this is a job for purescript-foreign then? Could add some more read variants for handling int/int with radix/float/NaN rejection.

[sharkdp]

In the meantime, purescript-integers includes a safe version of readInt:

fromString :: String -> Maybe Int

(see purescript/purescript-integers#17)

Also, the latest version of my purescript-numbers library includes the following safe alternative to readFloat:

fromString :: String -> Maybe Number

[safareli]

btw depending on Maybe could have been avoided using Alternative.

[JordanMartinez]

I think this should be closed as purescript-numbers has a fromString function that implements this. Otherwise, we'll need to make this repo depend on maybe.

[hdgarrood]

This repo does now depend on maybe, since #18 was merged, so we could update these to use Maybe now, and that arguably would make more sense since we are already using Maybe for the encode/decodeURI functions.

[hdgarrood]

Or, we could deprecate the library (#22) and sidestep the issue entirely.

[JordanMartinez]

When porting the Number-related code from this repo to purescript-numbers, the following decisions were made:

• readFloat was dropped in favor of the safer fromString
• readInt was dropped entirely. If it needs to be added again, one should submit a PR to purescript-integers.