How Can I Implement a Generic Comparison Operator in Go?

What is the comparable interface called?

In Go, there is no predefined interface that provides a generic comparison operator (<). Instead, you can define your own Less function to compare your types. The Less function takes two arguments of the same type and returns a boolean indicating whether the first argument is less than the second.

Here's an example of a Less function that can compare integers and strings:

func Less(a, b interface{}) bool {
    switch a.(type) {
    case int:
        if ai, ok := a.(int); ok {
            if bi, ok := b.(int); ok {
                return ai < bi
            }
        }
    case string:
        if ai, ok := a.(string); ok {
            if bi, ok := b.(string); ok {
                return ai < bi
            }
        }
    // ...
    default:
        panic("Unknown")
    }
    return false
}

You can use the Less function to insert elements into a sorted linked list:

func Insert(val interface{}, l *list.List) *list.Element {
    e := l.Front()
    if e == nil {
        return l.PushFront(val)
    }
    for ; e != nil; e = e.Next() {
        if Less(val, e.Value) {
            return l.InsertBefore(val, e)
        }
    }
    return l.PushBack(val)
}

This Insert function will maintain the linked list in sorted order based on the Less function.

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