{-# LANGUAGE OverloadedStrings #-} -- That library uses `Text` pervasively. This pragma permits to use-- String literal when a Text is needed.moduleMainwhereimportControl.Concurrent.Async (wait) importData.Aeson-- It requires to have `aeson` package installed. Note that EventStore doesn't constraint you to JSON-- format but putting common use aside, by doing so you'll be able to use some interesting EventStore-- features like its Complex Event Processing (CEP) capabality.importDatabase.EventStore-- Note that imports 'NonEmpty' data constructor and 'nonEmpty' function from-- 'Data.List.NonEmpty'.main::IO() main =do-- A common pattern with an EventStore connection is to create a single instance only and pass it-- wherever you need it (it's threadsafe). It's very important to not consider an EventStore connection like-- its regular SQL counterpart. An EventStore connection will try its best to reconnect-- automatically to the server if the connection dropped. Of course that behavior can be tuned-- through some settings. conn <- connect defaultSettings (Static"127.0.0.1"1113) let js = object ["isHaskellTheBest".=True] -- (.=) comes from Data.Aeson module. evt = createEvent "programming"Nothing (withJson js) -- Appends an event to a stream named `languages`. as <- sendEvent conn (StreamName"languages") anyVersion evt Nothing-- EventStore interactions are fundamentally asynchronous. Nothing requires you to wait-- for the completion of an operation, but it's good to know if something went wrong. _ <- wait as -- Again, if you decide to `shutdown` an EventStore connection, it means your application is-- about to terminate. shutdown conn -- Make sure the EventStore connection completes every ongoing operation. For instance, if-- at the moment we call `shutdown` and some operations (or subscriptions) were still pending,-- the connection aborted all of them. waitTillClosed conn