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// Package list implements persistent list.
package list
// List is a persistent list.
type List interface {
// Len returns the number of values in the list.
Len() int
// Cons returns a new list with an additional value in the front.
Cons(interface{}) List
// First returns the first value in the list.
First() interface{}
// Rest returns the list after the first value.
Rest() List
}
// Empty is an empty list.
var Empty List = &list{}
type list struct {
first interface{}
rest *list
count int
}
func (l *list) Len() int {
return l.count
}
func (l *list) Cons(val interface{}) List {
return &list{val, l, l.count + 1}
}
func (l *list) First() interface{} {
return l.first
}
func (l *list) Rest() List {
return l.rest
}
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