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Comment by jsbg | Hacker News Reader

In production Haskell you need to combine monads using e.g. monad transformers and this is significantly more complicated than just understanding how bind works. It also requires a lot of boilerplate code and any errors there are not obvious to track down.

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Writing your own monad transformers is more complicated than understanding bind. Using standard ones isn't: swap out `State s a` for `MonadState s m => m a` (or whatever the relevant effects are) and put `lift` where the compiler tells you to, and you're 90% of the way there.

The other 10% is stacking the appropriate sequence of `FooBarT (BarBazT ... )` at the entry point to your program, which is admittedly pretty tedious.

> In production Haskell you need to combine monads using e.g. monad transformers

In some workplaces, yes. However it's pretty tenable to use https://www.parsonsmatt.org/2018/03/22/three_layer_haskell_c... with no or few additional monads.

Alternatively, you can have just a few people that understand how to compose Monads and many others writing code within them.

I'm not sure if I think it's a best practice by any means, but it's a pattern I've seen that avoids having to include monad transformers in onboarding.

Also a much simpler alternative in my opinion to monad transformers is effectful:

https://github.com/haskell-effectful/effectful

Here's a talk on it:

https://www.youtube.com/watch?v=BUoYKBLOOrE

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