Difficult to introduce fallbacks when parseQuality fails

[Zankoku-Okuno]

In #1, I suggested that some sort of a -> Float -> Quality a function was unnecessary, but now that I'm using this library more, I think that was a poor idea, mainly for this reason:

fromMaybe (fromJust $ parseQuality "*/*") $
    parseQuality =<< lookup "Accept" (Wai.requestHeaders req)

Or in English, when there is no Accept header (or it's invalid), then I want to behave as if the client will accept anything. The code above is a workaround, but while I know the fromJust will work, I've developed a special enmity towards this particular partial function. It would be much better to replace (fromJust $ ...) with something like ("*/*" `q` 1) (though probably q isn't the best name... but I'll let you sort that out).

And, to answer the question from #1 about a fractional vs. integral argument, I think the fractional is the clearest. After all, if it's written 0.8 in the header, it may as well be written 0.8 in Haskell.

[zmthy]

Okay. I think I might actually just make the argument a string and reuse readQ. I won't have time to get on top of this for at least two weeks but it should be a pretty simple addition.

[zmthy]

Are you ever building quality values that don't have a quality of 1?

[Zankoku-Okuno]

Re building non-1 quality values: I think it's possible. My current use-case can afford to be a toy, but I could easily see someone building a server that fills in a default accept header along the lines of text/html,*/*;q=0.9.

[zmthy]

Okay, I've pushed to develop. I've exposed the maxQuality and minQuality functions, as well as a new quality function that uses readQ with a default error message. I've also prepped to bump the version to 1.0, let me know what you think and I'll finalise the release and publish to Hackage.

[zmthy]

Totally forgot about this. Let me know if you have any thoughts, I'll push the release soon.

[Zankoku-Okuno]

Well, you're not alone in forgetting :)

I think this kills the issue. I was going back-and-forth on whether an IsString instance would be good, but IsString a => IsString (Quality a) seems way too general to be a good idea.

I did have an unrelated idea before you publish, which I've put in #21 for organization purposes.