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wiki: update Range.md for Go 1.23 for-range additions #86

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28 changes: 21 additions & 7 deletions Range.md
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Expand Up @@ -6,7 +6,7 @@ Spec: https://go.dev/ref/spec#For_statements

## Summary

A range clause provides a way to iterate over an array, slice, string, map, or channel.
A range clause provides a way to iterate over an array, slice, string, map, channel, integer, or function.

## Example

Expand All @@ -22,18 +22,32 @@ for v := range myChannel {
for i, v := range myArray {
log.Printf("array value at [%d]=%v", i, v)
}

// Range over integer (Go 1.23+)
for i := range myInteger {
log.Printf("i=%d", i) // 0, 1, ..., myInteger-1
}

// Range over function (Go 1.23+)
for k, v := range myIter {
log.Printf("key=%v, value=%v", k, v)
}
```

## Reference

If only one value is used on the left of a range expression, it is the 1st value in this table.

| Range expression | 1st value | 2nd value (optional) | notes |
| :----------------------------------------- | :------------- | :------------------- | :------------------------------------------------- |
| array or slice a `[n]E`, `*[n]E`, or `[]E` | index `i int` | `a[i]` E |
| string s string type | index `i int` | rune `int` | range iterates over Unicode code points, not bytes |
| map m `map[K]V` | key `k K` | value `m[k]` V |
| channel c chan E | element `e E` | _none_ |
| Range expression | 1st value | 2nd value (optional) | notes |
| :------------------------------------------- | :------------- | :------------------- | :----------------------------------------------------------------------- |
| array or slice a `[n]E`, `*[n]E`, or `[]E` | index `i int` | `a[i]` E | |
| string s string type | index `i int` | rune `int` | range iterates over Unicode code points, not bytes |
| map m `map[K]V` | key `k K` | value `m[k]` V | |
| channel c `chan E`, `<-chan E` | element `e E` | _none_ | |
| integer value n integer type, or untyped int | value `i T` | _none_ | `T` is the type of `n`. If n <= 0, the loop does not run any iterations. |
| function, 0 values f `func(func() bool)` | _none_ | _none_ | |
| function, 1 value f `func(func(V) bool)` | value `v V` | _none_ | |
| function, 2 values f `func(func(K, V) bool)` | key `k K` | value `v V` | |

## Gotchas

Expand Down