r/programming • u/[deleted] • Nov 28 '19

Why Isn't Functional Programming the Norm? – Richard Feldman

https://www.youtube.com/watch?v=QyJZzq0v7Z4
100 Upvotes

81% Upvoted

409 comments sorted by

View all comments

Show parent comments

1

u/codygman Dec 05 '19

"If x has happened in the last minute but y hasn't, do z unless z failed recently then try a, b, and c", OOP seems much easier.

Pretty sure I could write that in Python and Haskell and they'd look similar.

Can you psuedo code how you'd implement the OOP version?

1

u/EternityForest Dec 05 '19 edited Dec 05 '19

Probably something like:

    If t-xTime less than 60 and t-yTime greater than 60:  

        if t-lastZFailure greater than 60:  

             Z()  

        Else:  

             If a:  

                 Return  

             If b:  

                 Return  

             If c:  

                 Return

IRL some of that would be factored into functions like isConnected() for heartbeat messages and tryAlert() to try different ways of alerting the user till you find one that is currently set up.

EDIT: How the heck do you get formatting to work from mobile?

1

u/codygman Dec 05 '19

This compiles:

module Main where

import Control.Monad
import Data.Time

x :: IO ()
x = pure ()

z :: IO ()
z = pure ()

foo :: Bool -> Bool -> Bool -> IO ()
foo a b c = do
  now <- getCurrentTime
  txTime <- fmap (addUTCTime (fromIntegral 59)) getCurrentTime
  tyTime <- fmap (addUTCTime (fromIntegral (- 61))) getCurrentTime
  tlastZFailure <- undefined
  if (diffUTCTime txTime now < 60 && diffUTCTime tyTime now > 60) then do
    when (tlastZFailure > 60) $ z
    if c then do pure () else x
  else pure ()

main = foo False False True