User:Benmachine/New network package

This concept originally arose as "fix up the network package" to address the following perceived flaws:

• Timeout socket options are unusable because setSockOpt takes an Int but they want a struct timeval. This can't be worked around because the underlying C import is not exposed and anyway is imported with the wrong type.
• Only Network.URI uses parsec, and most users of network probably don't use that module, so the extra dependency is probably unnecessary.
• The strange behaviour of UnixSocket with connectTo and accept leads me to believe that perhaps the address datatypes aren't well thought-out, as the API design allows for nonsensical requests to be made.
• The API is conditionally exposed based on what symbols are or are not defined on the compilation platform: in a sense this is good because unavailable APIs are caught at compile time, but the error message you get in this case is awkward and has led to spurious bug reports and confusion. It also doesn't seem possible to account for these API differences without yourself using CPP, which seems clumsy to me.
• The PortNumber newtype defines a Num instance despite the fact that it really doesn't often make sense to subtract ports. It doesn't define a Read instance.

The last few points especially started to suggest that a change to the existing package would probably be quite sweeping and API-breaking, so the idea mutated into "design a new network package minus the above flaws", since that was likely to be less troublesome for upgraders.