[Haskell-cafe] How to make boolean logic with IO Monad more expressive?

[Viktor Dukhovni]

> On May 27, 2019, at 1:07 AM, Magicloud Magiclouds <magicloud.magiclouds at gmail.com> wrote:
> 
> ```
> status <- ioOperation -- IO-ed anyway
> return $ pureComputing || (status && pure2)
> ```

With two helpers:

  (<&&>) :: IO Bool -> IO Bool -> IO Bool
  (<&&>) ma mb = ma >>= (\a -> if not a then return False else mb)

  (<||>) :: IO Bool -> IO Bool -> IO Bool
  (<||>) ma mb = ma >>= (\a -> if a then return True else mb)

you'd write:

  pure preComputing <||> (ioOperation <&&> pure pure2)

You could even define suitable fixity to make <&&> have higher
precedence than <||> and not need any parentheses.

-- 
	Viktor.