RequestHeader type edge cases

[maddie927]

The way the RequestHeader type is built brings up some possibly undefined edge cases. For example, this returns false:

ContentType applicationJSON == RequestHeader "Content-Type" "application/json"

And are these the same?

affjax $ defaultRequest { headers = [ ContentType applicationJSON ] }

affjax $ defaultRequest { headers = [ RequestHeader "Content-Type" "application/json" ] }

[garyb]

Yeah, this is a known thing, but something I haven't gotten around to sorting out. The HTTP headers shouldn't even be managed by this project really, I did start a more comprehensive version in contrib: https://github.com/purescript-contrib/purescript-http-headers but it needs plenty of work too.

Being able to pattern match on the headers is quite useful, so hiding the constructor and just providing a smart constructor that will ensure that the types are canonicalised isn't ideal, so maybe we either need to provide a canoncialiseHeader function, or perhaps a CanoncialHeader type that can be matched on or something like that.