Whether it has an effect is not an issue. The issue is that it is referentially transparent. Sure, we could have a discussion about whether partiality is an e

Whether it has an effect is not an issue. The issue is that it is referentially transparent. Sure, we could have a discussion about whether partiality is an effect. Someone, somewhere is having that discussion. If the Haskell committee had had this discussion in 1987, chances are we wouldn't have Haskell at all.