Skip to content

Instantly share code, notes, and snippets.

@pilgrim2go
Forked from rafkhan/hi_reddit.go
Last active August 29, 2015 14:08
Show Gist options
  • Save pilgrim2go/6dce5bbdecfa83ebf77b to your computer and use it in GitHub Desktop.
Save pilgrim2go/6dce5bbdecfa83ebf77b to your computer and use it in GitHub Desktop.
package main
import (
"fmt"
"reflect"
)
//function types
type mapf func(interface{}) interface{}
// func(value, memo) interface
type reducef func(interface{}, interface{}) interface{}
type filterf func(interface{}) bool
func main() {
a := []int{1, 2, 3, 4}
//Multiply everything by 2
b := Map(a, func(val interface{}) interface{} {
return val.(int) * 2
})
//Shoud be [2,4,6,8]
fmt.Println("MAP:", a, b)
//Summation
c := Reduce(b, 0, func(val interface{}, memo interface{}) interface{} {
return memo.(int) + val.(int)
})
//Should be 20
fmt.Println("REDUCE:", b, c)
//Check if the number is divisble by 4
d := Filter(b, func(val interface{}) bool {
return val.(int)%4 == 0
})
//Should be [4,8]
fmt.Println("FILTER:", b, d)
}
//Map(slice, func)
func Map(in interface{}, fn mapf) interface{} {
val := reflect.ValueOf(in)
out := make([]interface{}, val.Len())
for i := 0; i < val.Len(); i++ {
out[i] = fn(val.Index(i).Interface())
}
return out
}
//Reduce(slice, starting value, func)
func Reduce(in interface{}, memo interface{}, fn reducef) interface{} {
val := reflect.ValueOf(in)
for i := 0; i < val.Len(); i++ {
memo = fn(val.Index(i).Interface(), memo)
}
return memo
}
//Filter(slice, predicate func)
func Filter(in interface{}, fn filterf) interface{} {
val := reflect.ValueOf(in)
out := make([]interface{}, 0, val.Len())
for i := 0; i < val.Len(); i++ {
current := val.Index(i).Interface()
if fn(current) {
out = append(out, current)
}
}
return out
}
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment