Mercurial > hg > Members > tatsuki > functionaljava-master > core

comparison src/main/java/fj/data/Reader.java @ 0:fe80c1edf1be

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
add getLoop
author tatsuki
date Fri, 20 Mar 2015 21:04:03 +0900
parents
children
comparison
equal deleted inserted replaced
-1:000000000000 0:fe80c1edf1be
1 package fj.data;
2
3 import fj.F;
4 import fj.F1Functions;
5
6 /**
7 * The Reader monad (also called the function monad, so equivalent to the idea of F).
8 * Created by MarkPerry on 7/07/2014.
9 */
10 public class Reader<A, B> {
11
12 private F<A, B> function;
13
14 public Reader(F<A, B> f) {
15 function = f;
16 }
17
18 public F<A, B> getFunction() {
19 return function;
20 }
21
22 public static <A, B> Reader<A, B> unit(F<A, B> f) {
23 return new Reader<A, B>(f);
24 }
25
26 public static <A, B> Reader<A, B> constant(B b) {
27 return unit(a -> b);
28 }
29
30 public B f(A a) {
31 return function.f(a);
32 }
33
34 public <C> Reader<A, C> map(F<B, C> f) {
35 return unit(F1Functions.andThen(function, f));
36 }
37
38 public <C> Reader<A, C> andThen(F<B, C> f) {
39 return map(f);
40 }
41
42 public <C> Reader<A, C> flatMap(F<B, Reader<A, C>> f) {
43 return unit(a -> f.f(function.f(a)).f(a));
44 }
45
46 public <C> Reader<A, C> bind(F<B, Reader<A, C>> f) {
47 return flatMap(f);
48 }
49
50 }