Basic authentication stuff

[carlssonia]

To support user logging in snap-server (upcoming pull request).

[gregorycollins]

Hi,

Re: the continuation passing style -- I think it's cleaner to do it that way, personally. When implementing this stuff, you are always going to need a function like:

checkBasicAuthenticationCredentials :: MonadSnap m => (ByteString, ByteString) -> m ()

If you just make the type

getBasicAuthenticationCredentials :: MonadSnap m => m (ByteString, ByteString)

then you are still going to need to check what they gave you somehow anyways. One of the reasons I like "with" style here is that it's clear to the user what he's expected to provide to use the API.

Another thing I'd say is that if we do it your way, you don't want the return type to be a "Maybe" here, just use mzero if the authentication process fails.

[meiersi]

Hi @gregorycollins , I think this branch was accidentally closed because of my mistake in the in the issue number reference.