blob: f71492e35b86c37633ca5ced23ffa8ff912540ae (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
|
## Copyright (c) Eduardo Julian. All rights reserved.
## The use and distribution terms for this software are covered by the
## Eclipse Public License 1.0 (http://opensource.org/licenses/eclipse-1.0.php)
## which can be found in the file epl-v10.html at the root of this distribution.
## By using this software in any fashion, you are agreeing to be bound by
## the terms of this license.
## You must not remove this notice, or any other, from this software.
(;import lux
(lux/control (monoid #as m #refer #all)
(functor #as F #refer #all)
(monad #as M #refer #all)))
## [Types]
(deftype #export (Writer l a)
(, l a))
## [Structures]
(defstruct #export Writer/Functor (All [l]
(Functor (Writer l)))
(def (F;map f fa)
(let [[log datum] fa]
[log (f datum)])))
(defstruct #export (Writer/Monad mon) (All [l]
(-> (Monoid l) (Monad (Writer l))))
(def M;_functor Writer/Functor)
(def (M;wrap x)
[(:: mon m;unit) x])
(def (M;join mma)
(let [[log1 [log2 a]] mma]
[(:: mon (m;++ log1 log2)) a])))
|
