Editing Cloud Haskell (section)

== Migration from <tt>remote</tt> ==

Here are some suggestions that might ease the migration from the Cloud Haskell prototype <tt>remote</tt> to <tt>distributed-process</tt>.

* The "implicit" type of mkClosure has changed (implicit because mkClosure is a Template Haskell function). In <tt>distributed-process</tt> mkClosure takes a function of type <tt>T1 -> T2</tt> and returns a function of type <tt>T1 -> Closure T2</tt>. In other words, the first argument to your function becomes the closure environment; if you want two items in your closure environment, create a function of type <tt>(T1, T2) -> T3</tt>; if you want none, create a function of type <tt>() -> T1</tt>.

* <tt>distributed-process</tt> follows the naming conventions in ''Towards Haskell in the Cloud'' rather than in <tt>remote</tt> so the functions that deal with typed channels are called <tt>sendChan</tt>, <tt>receiveChan</tt> and <tt>newChan</tt> instead of <tt>sendChannel</tt>, <tt>receiveChannel</tt> and <tt>newChannel</tt>. 

* <tt>sendChan</tt>, <tt>receiveChan</tt> (and <tt>send</tt>) never fail in <tt>distributed-process</tt> (in <tt>remote</tt> they might throw a <tt>TransmitException</tt>). Instead, if you want to be notified of communication failure, you need to use <tt>monitor</tt> or <tt>link</tt>.

* The function <tt>forkProcess</tt> in <tt>remote</tt> is called <tt>spawnLocal</tt> in <tt>distributed-process</tt>

* The <tt>Process</tt> monad is called <tt>Process</tt> in <tt>distributed-process</tt> (rather than <tt>ProcessM</tt>). Similarly, the type <tt>Match</tt> replaces <tt>MatchM</tt> (and is no longer a monad).

* Initialization is different. See the documentation of of the [http://hackage.haskell.org/packages/archive/distributed-process-simplelocalnet/latest/doc/html/Control-Distributed-Process-Backend-SimpleLocalnet.html Control.Distributed.Process.SimpleLocalnet] to get started (note that the master/slave distinction in SimpleLocalnet is optional and does not need to be used).

* Peer discovery is different. The functions <tt>getPeers</tt> and <tt>nameQuery</tt> are no longer available. The function <tt>findPeers</tt> from <tt>SimpleLocalnet</tt> replaces some, but not all, of the functionality of <tt>getPeers</tt>. You can use <tt>whereisRemoteAsync</tt> to find processes that have been registered by name.