3 ms·

I'm also pretty sure that its immaterial if Haskell does 1 or not. This is an implementation detail and not at all important to something being a Monad or not.

• tome 10mo ago
  Ah! My favourite Haskell discussion. So, consider these two programs, the first in Haskell: main :: IO () main = do foo foo foo :: IO () foo = putStrLn "Hello" and the second in Python: def main(): foo() foo() def foo(): print("Hello") For the Python one I'd say "I/O is done inside `foo` before returning". Would you? If not, why not? And if so, what purpose does it serve to not say the same for the Haskell?
  • adastra22 10mo ago
    My Haskell is rusty enough that I don’t know the proper syntax for it, but you can make a program that calls foo and then throws away / never uses the IO computation. Because Haskell is lazy, “Hello” will never be printed.
    • tome 10mo ago
      You can do this main = do let x = foo putStrLn "foo was never executed" but you can also do this def main(): x = foo print("foo was never executed") What's the difference?