move sort func into separate file

main.go

@@ -32,37 +32,21 @@ func main() {
 	}
 }
 
-type letter struct {
-	r     rune
-	count int
-}
-
-func (l letter) String() string {
-	return fmt.Sprintf("%v: %d", string(l.r), l.count)
-}
-
 type result struct {
 	name string
 	h    histogram
 }
-
 type results []result
 
-func (r results) Len() int      { return len(r) }
-func (r results) Swap(i, j int) { r[i], r[j] = r[j], r[i] }
-func (r results) Less(i, j int) bool {
-	if len(r[i].h) == 0 || len(r[j].h) == 0 {
-		return false
-	}
-	return r[i].h[0].count > r[j].h[0].count
-}
-
 type histogram []letter
 
-func (n histogram) Len() int      { return len(n) }
-func (n histogram) Swap(i, j int) { n[i], n[j] = n[j], n[i] }
-func (n histogram) Less(i, j int) bool {
-	return n[i].count > n[j].count
+type letter struct {
+	r     rune
+	count int
+}
+
+func (l letter) String() string {
+	return fmt.Sprintf("%v: %d", string(l.r), l.count)
 }
 
 func freq(in string) histogram {

sort.go

@@ -0,0 +1,16 @@
+package main
+
+func (r results) Len() int      { return len(r) }
+func (r results) Swap(i, j int) { r[i], r[j] = r[j], r[i] }
+func (r results) Less(i, j int) bool {
+	if len(r[i].h) == 0 || len(r[j].h) == 0 {
+		return false
+	}
+	return r[i].h[0].count > r[j].h[0].count
+}
+
+func (n histogram) Len() int      { return len(n) }
+func (n histogram) Swap(i, j int) { n[i], n[j] = n[j], n[i] }
+func (n histogram) Less(i, j int) bool {
+	return n[i].count > n[j].count
+}