blob: 6911ef0159196f4c215c0062c5308a5d81669c84 (
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
|
(.module:
[library
[lux #*
[abstract
[functor (#+ Functor)]
[apply (#+ Apply)]
["." monad (#+ Monad do)]]
[control
["." try (#+ Try)]]
[data
["." text
["%" format (#+ format)]]
[collection
["." list ("#\." fold)]]]]]
[//
["." exception (#+ Exception exception:)]])
(type: (Cleaner r !)
(-> r (! (Try Any))))
(type: #export (Region r ! a)
{#.doc (doc "A region where resources may be be claimed and where a side-effecting computation may be performed."
"Every resource is paired with a function that knows how to clean/reclaim it, to make sure there are no leaks.")}
(-> [r (List (Cleaner r !))]
(! [(List (Cleaner r !))
(Try a)])))
(def: separator
Text
(format text.new_line
"-----------------------------------------" text.new_line
"-----------------------------------------" text.new_line
"-----------------------------------------" text.new_line
text.new_line))
(exception: #export [a] (clean_up_error {error Text}
{output (Try a)})
(format error
(case output
(#try.Success _)
""
(#try.Failure error|output)
(format separator
error|output))))
(def: (clean clean_up output)
(All [a] (-> (Try Any) (Try a) (Try a)))
(case clean_up
(#try.Success _)
output
(#try.Failure error)
(exception.except ..clean_up_error [error output])))
(def: #export (run monad computation)
{#.doc (doc "Executes a region-based computation, with a side-effect determined by the monad.")}
(All [! a]
(-> (Monad !) (All [r] (Region r ! a))
(! (Try a))))
(do {! monad}
[[cleaners output] (computation [[] (list)])]
(|> cleaners
(monad.map ! (function (_ cleaner) (cleaner [])))
(\ ! map (list\fold clean output)))))
(def: #export (acquire monad cleaner value)
{#.doc (doc "Acquire a resource while pairing it a function that knows how to reclaim it.")}
(All [! a] (-> (Monad !) (-> a (! (Try Any))) a
(All [r] (Region r ! a))))
(function (_ [region cleaners])
(\ monad in [(#.Item (function (_ region) (cleaner value))
cleaners)
(#try.Success value)])))
(implementation: #export (functor super)
(All [!]
(-> (Functor !)
(All [r] (Functor (Region r !)))))
(def: (map f)
(function (_ fa)
(function (_ region+cleaners)
(\ super map
(function (_ [cleaners' temp])
[cleaners' (case temp
(#try.Success value)
(#try.Success (f value))
(#try.Failure error)
(#try.Failure error))])
(fa region+cleaners))))))
(implementation: #export (apply super)
(All [!]
(-> (Monad !)
(All [r] (Apply (Region r !)))))
(def: &functor
(..functor (get@ #monad.&functor super)))
(def: (apply ff fa)
(function (_ [region cleaners])
(do super
[[cleaners ef] (ff [region cleaners])
[cleaners ea] (fa [region cleaners])]
(case ef
(#try.Success f)
(case ea
(#try.Success a)
(in [cleaners (#try.Success (f a))])
(#try.Failure error)
(in [cleaners (#try.Failure error)]))
(#try.Failure error)
(in [cleaners (#try.Failure error)]))))))
(implementation: #export (monad super)
(All [!]
(-> (Monad !)
(All [r] (Monad (Region r !)))))
(def: &functor
(..functor (get@ #monad.&functor super)))
(def: (in value)
(function (_ [region cleaners])
(\ super in [cleaners (#try.Success value)])))
(def: (join ffa)
(function (_ [region cleaners])
(do super
[[cleaners efa] (ffa [region cleaners])]
(case efa
(#try.Success fa)
(fa [region cleaners])
(#try.Failure error)
(in [cleaners (#try.Failure error)]))))))
(def: #export (failure monad error)
{#.doc (doc "Immediately fail with this 'message'.")}
(All [! a]
(-> (Monad !) Text
(All [r] (Region r ! a))))
(function (_ [region cleaners])
(\ monad in [cleaners (#try.Failure error)])))
(def: #export (except monad exception message)
{#.doc (doc "Fail by throwing/raising an exception.")}
(All [! e a]
(-> (Monad !) (Exception e) e
(All [r] (Region r ! a))))
(failure monad (exception.error exception message)))
(def: #export (lift monad operation)
{#.doc (doc "Lift an effectful computation into a region-based computation.")}
(All [! a]
(-> (Monad !) (! a)
(All [r] (Region r ! a))))
(function (_ [region cleaners])
(\ monad map
(|>> #try.Success [cleaners])
operation)))
|
