Go 1.23 Released

Re:Go 1.23 Released by metadat on Tuesday August 13, 2024 @05:14PM (#41239926)

I want to understand the purpose of maps.All().

In the example:

  m := map[string]int{"a": 1, "b": 2, "c": 3}
  
  for k, v := range maps.All(m) {
   fmt.Printf("%v:%v ", k, v)
  }
  
  fmt.Println("")
  
  for k, v := range m {
   fmt.Printf("%v:%v ", k, v)
  }

These both output the same thing. What's the point of the addition?

Slices.All() seems similarly redundant and pointless.

Surely I must be misunderstanding something, I hope.

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Re:Go 1.23 Released by sakjur on Tuesday August 13, 2024 @05:34PM (#41240100)

They’re useful because they let you pass a slice or map to something built to handle the new func(func (…) bool) style iterators.

If I create a IterateOver(fn func(func (K, V any) bool)) function, you cannot pass a slice since that doesn’t match fn’s type, but if you wrap it with slices.All it’ll work.

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Re:Go 1.23 Released by ianlancetaylor on Tuesday August 13, 2024 @06:08PM (#41240349)

You can use it with other functions that use iterators. For example, here is code that makes a copy of a map keeping only the even keys.

  maps.Collect(xiter.Filter2(func(k, v int) bool { return k%2 == 0 }, maps.All(m)))

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