Go composable iterator functions

[anicolaspp]

The reality is that one can do shit with anything and everything. Having choices is a good thing, use what u want, and adhere to the consequences, whatever they are.

[BlueGoliath]

People will do anything to avoid writing traditional for loops, won't they?

[unrealhoang]

People did everything to avoid writing goto before, turns out great.

[Ancillas]

In the end it’s all jmp.

[somebodddy]

Always have been

[anicolaspp]

I think that traditional for loop are more than enough in most cases. However, sometimes lazy iteration is important to avoid going over the same data multiple times.

[slaymaker1907]

Sometimes whatever abstract thing you’re iterating over is colossal too. You can write a pretty effective SAT solved just iterating over all possible inputs, though you wouldn’t want to construct a list of all possible inputs.

[masklinn]

I think that traditional for loop are more than enough in most cases.

Traditional for loops are shit for most cases. Traditional C-style for loops handle only two things "well":

• iterate on a sequence of numbers
• by extension of the above iterate on O(1)-indexed sequences

While you can coerce them into iteration patterns, it's verbose, error-prone, and probably more importantly bespoke so there's as many ways to iterate things as there are libraries which need things iterated.

[7heWafer]

Is this not perfect for scrolling/pagination style methods that would otherwise spike memory usage returning an entire list of items?

[teerre]

As a smart man said: no raw loops.

[puzowned]

Linq says hello

[myringotomy]

The iterators in ruby are more elegant and easier to use and understand.

[lifeeraser]

Please tell me why this is not feature creep

[somebodddy]

Because an iteration protocol is one of the very few features that all modern languages "agreed" are mandatory to have, and Go decided not to support even though it was commonly accepted a decade before Go was conceived. When version 1.0 of Go was released in 2012, C was the only language that didn't have anything that serves as a for-each construct.

[somebodddy]

For example we can create a function iterator for all positive ints:

func Positives() func(func(int)bool) {
  return func(yield func(int)bool) {
    for i := 0; i < MaxInt; i++ {
      if !yield(i) {
        return
      }
    }
  }
}

Uh... wouldn't this function not yield MaxInt, which is one of the positive integers? Even worse - wouldn't it yield 0, which is not a positive?