Read response headers

[hdgarrood]

I'd like to be able to do things like ask if a response has a certain header, or get the value of a certain header in the response (if it exists).

Currently it seems impossible to do this, since the ResponseHeader data type doesn't export its constructor, and I don't see any functions for extracting this information from them.

[hdgarrood]

Oh - having seen RequestHeader, I suppose the motivation is to avoid a stringly-typed interface?

Would it be possible to expose some way of getting everything as just strings, possibly with a note in the documentation suggesting people use the stronger typed interface instead?

[garyb]

Yeah, exactly. Both types need work actually to be extended with common cases, but we could definitely do something to expose them as strings too - responseHeaderName :: ResponseHeader -> String, responseHeaderValue :: ResponseHeader -> String like there is for requestHeaderName. Would that do it?

[hdgarrood]

Yeah I think so - then presumably I could do something like response.headers # Data.Foldable.find (responseHeaderName >>> eq "Set-Cookie") # map responseHeaderValue to get the header value as a Just if it's there, and Nothing otherwise?

Also perhaps a newtype wrapper around String which makes equality and comparison case insensitive might be helpful here?

[garyb]

Yep, that's along the lines of what I was thinking. Case insensitive newtype for String comparisons sounds good too, would make a nice addition to purescript-strings.

[paf31]

Cf. http://hackage.haskell.org/package/case-insensitive 👍

[garyb]

Ok, I've added those functions now. Although on further reflection neither responseHeaderValue or requestHeaderValue are quite right in the long run, there should probably be a phantom type on ResponseHeader and RequestHeader that determines their contained content type.