On Design Patterns in C++

Re:On Design Patterns in C++ by Privacy846 on Saturday December 19, 2020 @01:11PM (#25479585)

Design patterns are considered to be things that you can’t express directly in the language (that’s the Design Patterns book definition). Monads can definitely be expressed directly in Haskell. The only thing you can’t do is prove the Monad laws in Haskell (I think?).

Other languages, like e.g. Rust (because of lack of HKT), cannot express monads like Haskell can.

But yeah, you can definitely call it a design pattern if that’s what the culture around the language is like. But it would be like Java folks calling interfaces with default implementations for something goofy like “Interface with stateless implementations pattern”, and even they don’t go that far.

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Re:On Design Patterns in C++ by AnimalMuppet on Wednesday December 23, 2020 @12:28AM (#25514671)

Late reply; I didn't see this earlier.

But in Haskell, a lot of the time you don't use a monad because you want a monad. You use a monad to do something else - to log in a pure way, for example. That use of a monad to solve a particular problem is a pattern.

I'd even argue that it's using the pattern to compensate for a weakness of the language. (Or, if you prefer, to help with things that are difficult within the language design and philosophy.)

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