> But with Haskell, it seems a reverse process was followed. It starts with some (questionable?) assumptions like lazy evaluation is good and then builds on top

> But with Haskell, it seems a reverse process was followed. It starts with some (questionable?) assumptions like lazy evaluation is good and then builds on top of it. Haskell was created by researches who wanted to study properties of lazy functional programming. I’ve never heard anyone say they did it because lazy evaluation was “good”, it was their area of research. The co-creator has even said that if he had to do it over again it might be better if it were strictly evaluated. I worked in Haskell for a few years before switching over to a very closely related but strictly evaluated language, PureScript. The pureness and laziness of Haskell forced the creators to work out monads for IO which I find extremely useful. Haskell-like monads certainly can (and have) been implemented in strictly evaluated languages. I don’t miss implicit laziness very often, but I’ll say with partially applied functions, it’s nice to know that values will be calculated as needed and results shared across invocations once those functions are fully applied. That’s something I wish we had in PureScript. Note that in addition to laziness this also requires a compiler optimization that moves let bindings out of inner functions, aka let-floating. Laziness is also nice as it allows you to be very declarative, defining what things are without ever worrying about the calculations running when you don’t need the result. In practice it’s easy enough to create thunks manually and evaluate them when needed. Doing this can get tedious and the resulting code is less succinct.