blob: 14563e534c1aaa5028886623b8ae70c06707323b (
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
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
|
## Copyright (c) Eduardo Julian. All rights reserved.
## This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
## If a copy of the MPL was not distributed with this file,
## You can obtain one at http://mozilla.org/MPL/2.0/.
(;module:
lux
(lux (control functor
applicative
monad
eq)
[io #- run]
(codata function)
(data (coll [list])
text/format)
[compiler]
(macro ["s" syntax #+ syntax: Syntax]))
(.. ["&" promise]))
## [Types]
(type: #export (Chan a)
{#;doc "An asynchronous channel of values which may be closed.
Reading from a channel does not remove the read piece of data, as it can still be accessed if you have an earlier node of the channel."}
(&;Promise (Maybe [a (Chan a)])))
## [Syntax]
(syntax: #export (chan [?type (s;opt s;any)])
{#;doc (doc "Makes an uninitialized Chan (in this case, of Unit)."
(chan Unit)
"The type is optional."
(chan))}
(case ?type
(#;Some type)
(wrap (list (` (: (Chan (~ type))
(&;promise)))))
#;None
(wrap (list (` (&;promise))))))
## [Values]
(def: #export (filter p xs)
(All [a] (-> (-> a Bool) (Chan a) (Chan a)))
(do &;Monad<Promise>
[?x+xs xs]
(case ?x+xs
#;None (wrap #;None)
(#;Some [x xs']) (if (p x)
(wrap (#;Some [x (filter p xs')]))
(filter p xs')))))
(def: #export (write value chan)
{#;doc "Write to a channel, so long as it's still open."}
(All [a] (-> a (Chan a) (IO (Maybe (Chan a)))))
(case (&;poll chan)
(^template [<case> <chan-to-write>]
<case>
(do Monad<IO>
[#let [new-tail (&;promise)]
done? (&;resolve (#;Some [value new-tail]) <chan-to-write>)]
(if done?
(wrap (#;Some new-tail))
(write value <chan-to-write>))))
([#;None chan]
[(#;Some (#;Some [_ chan'])) chan'])
_
(:: Monad<IO> wrap #;None)
))
(def: #export (close chan)
(All [a] (-> (Chan a) (IO Bool)))
(case (&;poll chan)
(^template [<case> <chan-to-write>]
<case>
(do Monad<IO>
[done? (&;resolve #;None <chan-to-write>)]
(if done?
(wrap true)
(close <chan-to-write>))))
([#;None chan]
[(#;Some (#;Some [_ chan'])) chan'])
_
(:: Monad<IO> wrap false)
))
(def: (pipe' input output)
(All [a] (-> (Chan a) (Chan a) (&;Promise Unit)))
(do &;Monad<Promise>
[?x+xs input]
(case ?x+xs
#;None (wrap [])
(#;Some [x input']) (case (io;run (write x output))
#;None
(wrap [])
(#;Some output')
(pipe' input' output')))))
(def: #export (pipe input output)
{#;doc "Copy/pipe the contents of a channel on to another."}
(All [a] (-> (Chan a) (Chan a) (&;Promise Unit)))
(do &;Monad<Promise>
[_ (pipe' input output)]
(exec (io;run (close output))
(wrap []))))
(def: #export (merge xss)
{#;doc "Fuse all the elements in a list of channels by piping them onto a new output channel."}
(All [a] (-> (List (Chan a)) (Chan a)))
(let [output (chan ($ +0))]
(exec (do &;Monad<Promise>
[_ (mapM @ (lambda [input] (pipe' input output)) xss)]
(exec (io;run (close output))
(wrap [])))
output)))
(def: #export (fold f init xs)
{#;doc "Asynchronous fold over channels."}
(All [a b] (-> (-> b a (&;Promise a)) a (Chan b) (&;Promise a)))
(do &;Monad<Promise>
[?x+xs xs]
(case ?x+xs
#;None (wrap init)
(#;Some [x xs']) (do @
[init' (f x init)]
(fold f init' xs')))))
(def: (no-dups' eq last-one xs)
(All [a] (-> (Eq a) a (Chan a) (Chan a)))
(let [(^open) eq]
(do &;Monad<Promise>
[?x+xs xs]
(case ?x+xs
#;None (wrap #;None)
(#;Some [x xs']) (if (= x last-one)
(no-dups' eq last-one xs')
(wrap (#;Some [x (no-dups' eq x xs')])))))))
(def: #export (no-dups eq xs)
{#;doc "Multiple consecutive equal values in the input channel will just be single value in the output channel."}
(All [a] (-> (Eq a) (Chan a) (Chan a)))
(let [(^open) eq]
(do &;Monad<Promise>
[?x+xs xs]
(case ?x+xs
#;None (wrap #;None)
(#;Some [x xs']) (wrap (#;Some [x (no-dups' eq x xs')]))))))
(def: #export (consume xs)
{#;doc "Reads the entirety of a channel's contents and returns them as a list."}
(All [a] (-> (Chan a) (&;Promise (List a))))
(do &;Monad<Promise>
[?x+xs' xs]
(case ?x+xs'
#;None
(wrap #;Nil)
(#;Some [x xs'])
(do @
[=xs (consume xs')]
(wrap (#;Cons x =xs))))))
(def: #export (as-chan p)
(All [a] (-> (&;Promise a) (Chan a)))
(do &;Monad<Promise>
[x p]
(wrap (#;Some [x (wrap #;None)]))))
## [Structures]
(struct: #export _ (Functor Chan)
(def: (map f xs)
(:: &;Functor<Promise> map
(lambda [?x+xs]
(case ?x+xs
#;None #;None
(#;Some [x xs']) (#;Some [(f x) (map f xs')])))
xs)))
(struct: #export _ (Applicative Chan)
(def: functor Functor<Chan>)
(def: (wrap a)
(let [(^open) &;Monad<Promise>]
(wrap (#;Some [a (wrap #;None)]))))
(def: (apply ff fa)
(let [fb (chan ($ +1))]
(exec (let [(^open) Functor<Chan>]
(map (lambda [f] (pipe (map f fa) fb))
ff))
fb))))
(struct: #export _ (Monad Chan)
(def: applicative Applicative<Chan>)
(def: (join mma)
(let [output (chan ($ +0))]
(exec (let [(^open) Functor<Chan>]
(map (lambda [ma]
(pipe ma output))
mma))
output))))
|
