wrangling the internet of things with haskell production haskell - - PowerPoint PPT Presentation

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wrangling the internet of things with haskell production
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wrangling the internet of things with haskell production haskell - - PowerPoint PPT Presentation

Sep 01, 2022 406 likes •1.1k views

wrangling the internet of things with haskell production haskell Reid Draper @reiddraper production haskell Reid Draper @reiddraper production haskell today production haskell at helium 12 months in lowest defect rate lowest defect rate

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production haskell

Reid Draper @reiddraper

wrangling the internet of things with haskell

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production haskell

Reid Draper @reiddraper

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production haskell today

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production haskell at helium

12 months in

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lowest defect rate

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easiest to refactor lowest defect rate

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OSS libraries for everything* most enjoyable easiest to refactor lowest defect rate

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20k LOC

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5 developers 20k LOC

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6 production services 5 developers 20k LOC

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build deploy monitor test develop

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build deploy monitor test develop

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cabal hell

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cabal hell

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stack

haskellstack.org

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project specific snapshot ghc packages

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2 seconds 20k LOC

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  • rdeal

github.com/reiddraper/ordeal

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stack build self-contained executable

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build deploy monitor test develop

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app assets images favicon.ico javascript site.js stylesheet site.css bin app

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restart app ln -s app-370b347 current tar -xzf app-370b347.tgz

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restart app ln -s app-83181ad current

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60MB

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build deploy monitor test develop

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ekg

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stdout file syslog

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build deploy monitor test develop

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QuickCheck

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propEvent :: Event -> Bool propEvent a = Just a == decode (encode a)

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Event roundtrips in JSON: FAIL (0.04s) *** Failed! Falsifiable (after 1 test): Event {_severity = Error, _facility = Unspecified, _sampled = 1894-02-22 00:00:04.5986 UTC, _eventDetails = ElementDisconnect {_elementMAC = 8ec52584b2c82424}, _eventMessage = Nothing, _originator = http://www.ietf.org/rfc/rfc2396.txt, _reference = Just http://www.ietf.org/rfc/rfc2396.txt }

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Event roundtrips in JSON: FAIL (0.04s) *** Failed! Falsifiable (after 1 test): Event {_severity = Error, _facility = Unspecified, _sampled = 1894-02-22 00:00:04.5986 UTC, _eventDetails = ElementDisconnect {_elementMAC = 8ec52584b2c82424}, _eventMessage = Nothing, _originator = http://www.ietf.org/rfc/rfc2396.txt, _reference = Just http://www.ietf.org/rfc/rfc2396.txt }

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ghci> t 1894-02-22 00:00:04.5986 UTC ghci> Data.Aeson.encode t "\"1894-02-22T00:00:04.598Z\""

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build deploy monitor test develop

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postgresql-transactional

github.com/helium/postgresql-transactional

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lookupUser emailAddress = queryFirst [emailAddress] [sql| SELECT id, email, name, timezone FROM user_account
 WHERE email = ? |]

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foo

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foo bar

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foo bar baz

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foo bar baz quz

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foo bar baz quz buz

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foo bar baz quz buz fiz

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BEGIN BEGIN COMMIT COMMIT

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BEGIN BEGIN COMMIT COMMIT

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BEGIN BEGIN COMMIT COMMIT

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WARNING: there is already a transaction in progress WARNING: there is no transaction in progress

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foo bar baz quz buz fiz

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foo bar baz quz buz fiz

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foo bar baz quz buz

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lookupUser :: Connection -> Text -> IO (Maybe User) lookupUser connection emailAddress = queryFirst [emailAddress] [sql| SELECT id, email, name, timezone FROM user_account
 WHERE email = ? |] connection

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createUser :: Connection

  • > NewUser
  • > IO User

createOrganization :: Connection

  • > NewOrganization
  • > IO Organization

addUserToOrganization :: Connection

  • > User
  • > Organization
  • > IO ()
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createUserAndOrganization :: Connection

  • > NewUser
  • > IO ()

createUserAndOrganization connection newUser = withTransaction connection $ do let newOrganization = NewOrganization (newUser ^. name) user <- createUser connection newUser

  • rg <- createOrganization connection newOrganization

addUserToOrganization connection user org

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  • - NOTE: you MUST wrap this in a transaction!!

createUserAndOrganization :: Connection

  • > NewUser
  • > IO ()

createUserAndOrganization connection newUser = do let newOrganization = NewOrganization (newUser ^. name) user <- createUser connection newUser

  • rg <- createOrganization connection newOrganization

addUserToOrganization connection user org

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withTransaction conn $ do createUserAndOrganization conn newUser somethingElse conn

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types to the rescue

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lookupUser :: Connection -> Text -> IO (Maybe User) lookupUser :: Text -> PGTransaction (Maybe User)

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runPGTransaction :: PGTransaction a

  • > Postgres.Connection
  • > IO a
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createUserAndOrganization :: NewUser

  • > PGTransaction ()

createUserAndOrganization newUser = let newOrganization = NewOrganization (newUser ^. name) user <- createUser newUser

  • rg <- createOrganization newOrganization

addUserToOrganization user org foo = do createUserAndOrganization newUser somethingElse runPGTransaction foo connection

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notAllowed = do user <- createUser newUser someSlowSideEffectingThing return user

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notAllowed = do user <- createUser newUser someSlowSideEffectingThing :: IO () return user

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postgresql-transactional

github.com/helium/postgresql-transactional

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build deploy monitor test develop

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Reid Draper @reiddraper github.com/helium helium.com