> The religious focus on purity. The elm maintainer is an haskell user, and it shows. Can you believe that to read the current time or generate a random number, you must be within a component's update function, ask for one or the other and you will get your result later, asynchronously?

You say this like generating a random number is a small deal. In a sense this is very true! From the machine's perspective generating a random number is a quick operation. However, from the perspective of maintainers who come after you losing determinism is no small thing, and IMHO deserves to be marked clearly in the type system.