Generics in Golang 1.18, no need to write max / min anymore (maybe)

June 08, 2021


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One thing I do dislike in golang is that sometimes a simple task can be very tedious. One of them is getting maximum / minimum value of two integers.


The root cause of the tediousness of this task is the lack of generics in golang which means you can not implement a max/min function which accepts both integer and float numbers. As the built-in max function is math package accepts float64, the common fixes that peope use are:

  • Write a wrapper function for math.Max or math.Min to do type conversion
func max(x, y int) int {
  return int(math.Max(float64(x), float64(y)))
  • Write your own max function
func max(x, y int) int {
    if x < y {
        return y
    return x

You might think it is not too hard to implement any of the solutions above, but it is just a totally waste of time, especially when you are joining online contests or just practicing algorithms and data structure.

Generics to the Rescue

So with the new accepted proposal in golang 1.18, finally we can fix this issue once and for all (if the built-in math.Max & math.Min is updated). A quick and dirty way can be done like below:

type comparable interface {
  type int, int8, int16, int32, int64,
    uint, uint8, uint16, uint32, uint64, uintptr,
    float32, float64

func Max[T comparable](x, y T) T {
  return T(math.Max(float64(x), float64(y)))

A working version HERE

If similar code like above can be added to the built-in math library, we don’t need to do it ourselves anymore. I believe there are a lot more applications like this can make golang a more elegant and less-tedious language in the future. Looking forward to the release of this version next year. 😃

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Written by Jerome Wu / Wen-Chieh Wu / 吳文傑
Mantainer of tesseract.js and ffmpeg.wasm. Here is my personal writtings about software technologies