Go: reflection filter (https://play.golang.org/p/LI6iZgqW7J)

main.go

package main

import (
	"fmt"
	"reflect"
)

func assert(k bool, msg string) {
	if !k {
		panic(msg)
	}
}

func Filter(sliceptr interface{}, filter interface{}) {
	spv := reflect.ValueOf(sliceptr)
	assert(spv.Kind() == reflect.Ptr, "Filter: not pointer to slice")

	sv := spv.Elem()
	assert(sv.Kind() == reflect.Slice, "Filter: not pointer to slice")

	et := sv.Type().Elem()
	fnv := reflect.ValueOf(filter)
	fnt := fnv.Type()
	assert(fnt.Kind() == reflect.Func, "Filter: filter must be func")
	assert(fnt.NumIn() == 1 && fnt.NumOut() == 1, "Filter: filter must have one argument and one return")
	assert(et.ConvertibleTo(fnt.In(0)), "Filter: incompatible argument for type")
	assert(fnt.Out(0).Kind() == reflect.Bool, "Filter: incompatible return value")

	k := 0
	for i := 0; i < sv.Len(); i++ {
		elem := sv.Index(i)
		r := fnv.Call([]reflect.Value{elem})
		remove := r[0].Bool()
		if remove {
			continue
		}

		if i != k {
			sv.Index(k).Set(elem)
		}
		k++
	}

	sv.SetLen(k)
}

func main() {
	data := []int{1, 2, 5, 7, 2, 5, 5, 5, 5, 5, 3, 413}
	Filter(&data, func(v int) bool { return v == 5 })
	fmt.Println(data)
}