suzuki

hace 4 añosdiscuss

> If you have an interface with a single method, or something with a single varying piece of behavior, please strongly consider accepting a function instead.

Agreed. And if you prefer methods to functions, you can define methods on such a function type! In my LINQ in Go (https://github.com/nukata/linq-in-go), I define a higher order function type:

  type Enumerator[T any] func(yield func(element T))

and several methods on it, for example,

  // Where creates an Enumerator which selects elements by appling
  // predicate to each of them.
  func (loop Enumerator[T]) Where(predicate func(T) bool) Enumerator[T] {
        return func(yield func(T)) {
                loop(func(element T) {
                        if predicate(element) {
                                yield(element)
                        }
                })
        }
  }

Naturally, if you need another type parameter for a method, you must define it as a function. For example,

  // Select creates an Enumerator which applies f to each of elements.
  func Select[T any, R any](f func(T) R, loop Enumerator[T]) Enumerator[R] {
        return func(yield func(R)) {
                loop(func(element T) {
                        value := f(element)
                        yield(value)
                })
        }
  }

Now, with the function which converts a slice to an Enumerator,

  // From creates an Enumerator from a slice.
  func From[T ~[]E, E any](x T) Enumerator[E] {
        return func(yield func(E)) {
                for _, element := range x {
                        yield(element)
                }
        }
  }

you can write the following:

  seq := Select(func(e int) int { return e + 100 },
        From([]int{
                7, 8, 9,
        })).Where(func(e int) bool {
        return e%2 != 0
  })
  seq(func(e int) {
        Println(e)
  })
  // Output:
  // 107
  // 109

suzuki

hace 5 añosdiscuss

It is a "mojibake" of 三個和尚沒水喝[1].

[1] https://en.wikipedia.org/wiki/Three_Monks

suzuki

hace 5 añosdiscuss

From a Japanese perspective, it also sounds very unlikely. Go with UTF-8 strings is successful nowadays in Japan.

suzuki

hace 5 añosdiscuss

I agree with you. I wish Python 3 had strings as byte sequences mainly in UTF-8 as Python 2 had once and Go has now. Then things would be kept simple in Japan. Python 3 feels cumbersome. To handle a raw input as a string, you must decode it in some encoding first. It is a fragile process. It would be adequate to treat the input bytes transparently and put an optional stage to convert other encodings to UTF-8 if necessary.

suzuki

hace 6 añosdiscuss

I have written almost the identical Scheme interpreters in Ruby and Crystal: [1] and [2]. The biggest difference I have felt between them is the absence of good old Object, which can represent everything at runtime, from Crystal. I had to declare Obj and Val:

  class Obj
  end

  # Value operated by Scheme
  alias Val = Nil | Obj | Bool | String | Int32 | Float64 | BigInt

to define Cons Cell of Scheme:

  # Cons cell
  class Cell < Obj
    include Enumerable(Val)

    getter car : Val            # Head part of the cell
    property cdr : Val          # Tail part of the cell

    def initialize(@car : Val, @cdr : Val)
    end

    ...
  end # Cell

Note that you see generics, Enumerable(Val), and constructor arguments with '@' in the excerpt above.

As for performance, Crystal is faster than Ruby 8.6 times as interpreter and 39.4 times as compiler [3]. You can use Crystal as a superfast (and typed) Ruby interpreter, in a sense.

[1] https://github.com/nukata/little-scheme-in-ruby [2] https://github.com/nukata/little-scheme-in-crystal [3] https://github.com/nukata/little-scheme#performance

suzuki

hace 6 añosdiscuss

IANAL, but I believe you cannot put "(c) Your Name 2020" on Shakespeare's works in Japan and other countries. Their copyright acts protect the moral rights of authors[1][2]. So I think Zen's file headers would be violating the law in Japan and other countries.

[1] https://en.wikipedia.org/wiki/Moral_rights [2] http://www.japaneselawtranslation.go.jp/law/detail_main?id=2... (Copyright Act of Japan) Subsection 2 Moral Rights of Authors (Articles 18 to 20)

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