When FP? And When OOP? (2013)

Re:When FP? And When OOP? (2013) by rkangel on Monday January 28, 2019 @05:41AM (#19016438)

ADTs are common in statically typed FP languages (and others you mentioned like Rust and Kotlin). I have been working with Elixir a lot, and being dynamically typed the concept isn't appropriate.

Pattern matching is the concept that they all have in common, that I miss when it isn't available. You don't have the 'exhaustiveness' check in Elixir because it's not possible in a dynamic language (dialyzer aside), but it's still a very powerful tool.

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Re:When FP? And When OOP? (2013) by chriswarbo on Monday January 28, 2019 @06:49AM (#19016733)

I write Scheme code as if it had ADTs, e.g.

    (match payment
      [('invoice address     ) (foo address     )]
      [('card    card-details) (bar card-details)])

As you say, there's no exhaustiveness check; plus the language won't guarantee that the product types are adhered to. For example, someone might give us `('invoice card-details)` and the language wouldn't complain.

Racket's contract system can help with this; although it's very slow.

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