Monthly Downloads: 2
Programming language: Haskell
License: MIT License
Tags: Data    
Latest version: v0.1.0.0

cmf alternatives and similar packages

Based on the "Data" category.
Alternatively, view cmf alternatives based on common mentions on social networks and blogs.

Do you think we are missing an alternative of cmf or a related project?

Add another 'Data' Package



What is it

This library provides concurrent folds for commutative monoids.

This is useful when you have some IO-bound task which meets at least the following two conditions:

  1. It needs to be run over potentially many of the same type of input
  2. The output can be combined in a commutative fashion

How to use it

-- Example 1: Grabbing data from a bunch of nodes (represented as just IPv4 addresses)
{-# language PackageImports #-}

module Main (main) where

-- intended to be imported qualified
import qualified Cmf
import "ip" Net.IPv4 (IPv4)

main :: IO ()
main = do
  nodes <- readNodesFromFile "some_nodes.txt"
  -- the list monoid is 'commutative' if we don't care about ordering
  someData <- Cmf.foldMap reachOutToNodeAndGetData nodes
  print someData

data SomeData = SomeData
  deriving (Show)

reachOutToNodeAndGetData :: IPv4 -> IO [SomeData]
reachOutToNodeAndGetData = ...

readNodesFromFile :: FilePath -> IO [IPv4]
readNodesFromFile = ...
-- Example 2: Sending out emails concurrently
module Main (main) where

-- intended to be imported qualified
import qualified Cmf
import Data.Map (Map)

main :: IO ()
main = do
  emails <- getWhoShouldBeNotifiedOnEvent AccountSetupFinished
  errs <- Cmf.foldMapWithKey (\k v -> (:[]) <$> sendEmail k v) emails
  print errs

-- opaque data types, address and content of email
data EmailAddress = EmailAddress
  deriving (Show)
data EmailContent = EmailContent
  deriving (Show)
-- failed to send the email - address and error message
data EmailError = EmailError EmailAddress String
  deriving (Show)

sendEmail :: EmailAddress -> EmailContent -> IO (Either EmailError ())
sendEmail = ...

data Event = AccountSetupFinished | SomethingElse

getWhoShouldBeNotifiedOnEvent :: Event -> IO (Map EmailAddress EmailContent)
getWhoShouldBeNotifiedOnEvent = ...