Scala: What do “effect” and “effectful” mean in functional programming?

When you get started with functional programming (FP) a common question you’ll have is, “What is an effect in functional programming?” You’ll hear advanced FPers use the words effects and effectful, but it can be hard to find a definition of what these terms mean.

Scala: “IO monad doesn’t make a function pure; it just makes it obvious it’s impure” alvin July 21, 2018 - 11:15am

I always find it confusing when people claim that the IO monad somehow makes an impure function pure. Frankly, I think that argument does a confusing disservice to people who are trying to learn functional programming (FP).

Why Haskell has monads

“If it wasn’t for the problem of how to sequence input-output actions correctly, monads probably wouldn’t have appeared in Haskell. But once it was appreciated what they could do, all kinds of other uses quickly followed.”

~ Thinking Functionally with Haskell, Richard Bird