Map and Filter are nice because they let you reason locally about a single element in isolation. Reduce(Fold) forces you to reason globally about intermediate results. Reduce also forces you to conjure up a "zero" value of the relevant type, which isn't usually difficult but it does constitute some extra mental overhead.
> Reduce also forces you to conjure up a "zero" value of the relevant type
It's more accurately an identity. If you are multiplying the identity is 1. While I think most people are comfortable saying the sum of no elements is 0 it's perhaps less intuitive that the product of no elements is 1. This makes me think reduce might be preferred by those with a mathematical background.
snackbroken · · focus · HN ↗
globular-toast · · focus · HN ↗
It's more accurately an identity. If you are multiplying the identity is 1. While I think most people are comfortable saying the sum of no elements is 0 it's perhaps less intuitive that the product of no elements is 1. This makes me think reduce might be preferred by those with a mathematical background.