8 months of OCaml after 8 years of Haskell in production (2023)

Re:8 months of OCaml after 8 years of Haskell in production ... by steveklabnik on Tuesday December 03, 2024 @12:05PM (#42308430)

Idiomatic Rust would look like this:

    fn double(x: i32) -> i32 {
        2 * x
    }

The reason Rust requires types here is because global inference is computationally expensive and causes spooky action at a distance. The only real difference between your F# and this is the braces, which I do personally think makes code easier to read.

Of course there’s more overhead in smaller functions. I’d never write this code in Rust. I’d either inline it, or use a closure, which does allow for inference, and dropping the braces given that this is a one liner:

    |x| 2 * x

Different needs for different things.

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Re:8 months of OCaml after 8 years of Haskell in production ... by itishappy on Tuesday December 03, 2024 @12:24PM (#42308638)

    #  Rust
    let double = |x| 2 * x;
    double(3);

    // F#
    let double = (*) 2
    double 3

    -- Haskell
    let double = (*2)       
    double 3

    #  Python
    double = lambda x: 2 * x
    double(3)

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Re:8 months of OCaml after 8 years of Haskell in production ... by bmitc on Tuesday December 03, 2024 @01:22PM (#42309365)

If I am understanding that |x| 2 * x in Rust is an anonymous function, another F# equivalent is fun x -> 2 * x.

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Re:8 months of OCaml after 8 years of Haskell in production ... by neonsunset on Tuesday December 03, 2024 @01:38PM (#42309596)

The Haskell and F# examples above use partial application.

This also works:

  let zeroCount = numbers |> Seq.filter ((=) 0) |> Seq.length

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Re:8 months of OCaml after 8 years of Haskell in production ... by steveklabnik on Tuesday December 03, 2024 @06:21PM (#42312810)

It's a closure, not just an anonymous function, though it of course has an empty environment so it's not a significant difference in this case. Rust doesn't have syntax for anonymous functions, only closures.

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Re:8 months of OCaml after 8 years of Haskell in production ... by bmitc on Tuesday December 03, 2024 @01:19PM (#42309337)

I thought that the Rust playground was requiring me to use return, but I was mistaken. However, it actually lends to my original point though because I would wager that dropping the return was part of the influence of ML on the beginnings of Rust.

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Re:8 months of OCaml after 8 years of Haskell in production ... by steveklabnik on Tuesday December 03, 2024 @06:20PM (#42312804)

Expression orientation certainly comes from that general space, for sure.

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