Golang container/list creating a FindAll function - go

Question

I was wondering if this is the way to create and pass 'generic'(yeah I know, a sensitive word in GoLang) lists to a FindAll function.
Here's my attempt:
package main
import (
"container/list"
"fmt"
"strings"
)
func FindAll(lst *list.List, p func(interface{}) bool) *list.List {
ans := list.New()
for i := lst.Front(); i != nil; i = i.Next() {
if p(i.Value) {
ans.PushBack(i.Value)
}
}
return ans
}
func ConvertToInt(p func(int) bool) func(interface{}) bool {
return func(v interface{}) bool {
if value, ok := v.(int); ok {
if p(value) {
return true
} else {
return false
}
} else {
return false
}
}
}
func IsEven(n int) bool {
if n%2 == 0 {
return true
}
return false
}
func ConvertoString(p func(s string) bool) func(interface{}) bool {
return func(v interface{}) bool {
if value, ok := v.(string); ok {
if p(value) {
return true
} else {
return false
}
} else {
return false
}
}
}
func IsHello(str string) bool {
if strings.ToLower(str) == "hello" {
return true
} else {
return false
}
}
func main() {
fmt.Println("Find All Programs!\n\n")
lsti := list.New()
for i := 0; i < 11; i++ {
lsti.PushBack(i)
}
ansIsEven := FindAll(lsti, ConvertToInt(IsEven))
for i := ansIsEven.Front(); i != nil; i = i.Next() {
if value, ok := i.Value.(int); ok {
fmt.Printf("Found even: %d\n", value)
} else {
fmt.Println("Huh! What's that?")
}
}
}
I've been playing with this for a while and thought I'd better get the advice of the Go experts before I convince myself its correct.

Answer 1

The code as-is is pretty fine, but you should ask your self 2 questions:
1. Why shouldn't you use a typed slice? (interface{} performance is slow compared to the explicit type, although it will greatly improve in Go 1.7)
2. Would it be better to implement your specific type as a linked list?
Something like this can be much more efficient:
type IntList []int
func (l IntList) Filter(fn func(v int) bool) IntList {
var o IntList
for _, v := range l {
if fn(v) {
o = append(o, v)
}
}
return o
}
There's almost always a better alternative to container/list, however it all depends on your use case.