oeiuwq.com
An Algebraic Effect System for Golang.
Move core into package
+263
-256
+1
-1
abort/abort.go
+1
-1
abort/abort.go
+1
-1
abort/abort_test.go
+1
-1
abort/abort_test.go
+1
-1
abort/result.go
+1
-1
abort/result.go
-250
fx.go
-250
fx.go
···
1
-
package fx
2
-
3
-
type Fx[S, V any] struct {
4
-
// an immediate value
5
-
imm func() V
6
-
// the continuation of a suspended effect
7
-
sus func(S) Fx[S, V]
8
-
// the resume function of an stopped effect
9
-
res func() Fx[S, V]
10
-
}
11
-
12
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type FxPure[V any] = Fx[Nil, V]
13
-
type FxNil = FxPure[Nil]
14
-
15
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type Nil pnil
16
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type pnil struct{}
17
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18
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var PNil Nil = Nil(pnil{})
19
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var PureNil FxNil = Pure(PNil)
20
-
21
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func Pure[V any](v V) FxPure[V] { return Const[Nil](v) }
22
-
23
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func identity[V any](v V) V { return v }
24
-
25
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func Const[S, V any](v V) Fx[S, V] { return Fx[S, V]{imm: func() V { return v }} }
26
-
27
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func Pending[S, V any](f func(S) Fx[S, V]) Fx[S, V] { return Fx[S, V]{sus: f} }
28
-
29
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func Func[S, V any](f func(S) V) Fx[S, V] {
30
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return Pending(func(s S) Fx[S, V] { return Const[S](f(s)) })
31
-
}
32
-
33
-
func Ctx[V any]() Fx[V, V] { return Func(identity[V]) }
34
-
35
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// An stopped effect that panics if resumed.
36
-
// Only useful with Replace.
37
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//
38
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// For example, an Abort effect halts since it has no possible value for V
39
-
// but then its Handler can Replace the halted effect with an Error value.
40
-
// See: abort/result.go
41
-
func Halt[S, V any]() Fx[S, V] {
42
-
return Stop(func() Fx[S, V] {
43
-
return Fx[S, V]{
44
-
imm: func() V {
45
-
panic("tried to Resume a halted effect. try using Replace instead")
46
-
},
47
-
}
48
-
})
49
-
}
50
-
51
-
// Creates an stopped effect from a resume function
52
-
func Stop[S, V any](e func() Fx[S, V]) Fx[S, V] {
53
-
return Fx[S, V]{res: e}
54
-
}
55
-
56
-
// Resume an effect if it was previously stopped.
57
-
func Resume[S, V any](e Fx[S, V]) Fx[S, V] {
58
-
if e.res != nil {
59
-
return e.res()
60
-
}
61
-
if e.imm != nil {
62
-
return Const[S](e.imm())
63
-
}
64
-
return Pending(func(s S) Fx[S, V] { return Resume(e.sus(s)) })
65
-
}
66
-
67
-
// Replace with y if x is already Halted. Otherwise x continues.
68
-
func Replace[S, V any](y func() Fx[S, V]) func(Fx[S, V]) Fx[S, V] {
69
-
return func(x Fx[S, V]) Fx[S, V] {
70
-
if x.res != nil {
71
-
return y()
72
-
}
73
-
if x.imm != nil {
74
-
return Const[S](x.imm())
75
-
}
76
-
return Pending(func(s S) Fx[S, V] { return Replace(y)(x.sus(s)) })
77
-
}
78
-
}
79
-
80
-
// Continue an effect by transforming its immediate value into another effect.
81
-
func Then[T, U, S, V any](cmap func(T) S, fmap func(V) Fx[T, U]) func(Fx[S, V]) Fx[T, U] {
82
-
return func(e Fx[S, V]) Fx[T, U] {
83
-
if e.res != nil {
84
-
return Stop(func() Fx[T, U] { return Then(cmap, fmap)(e.res()) })
85
-
}
86
-
if e.imm != nil {
87
-
return fmap(e.imm())
88
-
}
89
-
return Pending(func(t T) Fx[T, U] { return Then(cmap, fmap)(e.sus(cmap(t))) })
90
-
}
91
-
}
92
-
93
-
type And[A, B any] func() (A, B)
94
-
95
-
func swap[A, B any](ab And[A, B]) And[B, A] {
96
-
var ba And[B, A] = func() (B, A) {
97
-
a, b := ab()
98
-
return b, a
99
-
}
100
-
return ba
101
-
}
102
-
103
-
func left[A, B any](ab And[A, B]) A {
104
-
a, _ := ab()
105
-
return a
106
-
}
107
-
108
-
func right[A, B any](ab And[A, B]) B {
109
-
_, b := ab()
110
-
return b
111
-
}
112
-
113
-
func ContraMap[V, S, R any](f func(R) S) func(Fx[S, V]) Fx[R, V] {
114
-
return func(e Fx[S, V]) Fx[R, V] {
115
-
if e.res != nil {
116
-
return Stop(func() Fx[R, V] { return ContraMap[V](f)(e.res()) })
117
-
}
118
-
if e.imm != nil {
119
-
return Const[R](e.imm())
120
-
}
121
-
return Pending(func(r R) Fx[R, V] {
122
-
return ContraMap[V](f)(e.sus(f(r)))
123
-
})
124
-
}
125
-
}
126
-
127
-
func MapM[S, U, V any](f func(U) Fx[S, V]) func(Fx[S, U]) Fx[S, V] {
128
-
return FlatCont(identity, identity, f)
129
-
}
130
-
131
-
func MapH[S, V, U any](f func(V) U) func(Fx[S, V]) Fx[S, U] {
132
-
return MapM(func(v V) Fx[S, U] { return Const[S](f(v)) })
133
-
}
134
-
135
-
func Map[S, V, U any](e Fx[S, V], f func(V) U) Fx[S, U] {
136
-
return MapH[S](f)(e)
137
-
}
138
-
139
-
func FlatMap[A, U, B, V any](e Fx[A, U], f func(U) Fx[B, V]) Fx[And[A, B], V] {
140
-
return FlatMapH[A](f)(e)
141
-
}
142
-
143
-
func FlatMapH[A, U, B, V any](f func(U) Fx[B, V]) func(Fx[A, U]) Fx[And[A, B], V] {
144
-
return FlatCont[And[A, B]](left, right, f)
145
-
}
146
-
147
-
func FlatCont[N, A, U, B, V any](amap func(N) A, bmap func(N) B, fmap func(U) Fx[B, V]) func(Fx[A, U]) Fx[N, V] {
148
-
return Then(amap, func(u U) Fx[N, V] { return Then(bmap, Const[N, V])(fmap(u)) })
149
-
}
150
-
151
-
func AndNil[S, V any](e Fx[S, V]) Fx[And[S, Nil], V] {
152
-
return Then[And[S, Nil], V](left, Const)(e)
153
-
}
154
-
155
-
func AndContra[A, B, V any](e Fx[A, V], f func(B) A) Fx[B, V] {
156
-
return ContraMap[V](f)(e)
157
-
}
158
-
159
-
func AndSwap[A, B, V any](e Fx[And[A, B], V]) Fx[And[B, A], V] {
160
-
return Then[And[B, A], V](swap[B, A], Const)(e)
161
-
}
162
-
163
-
func AndFlat[A, B, V any](e Fx[A, Fx[B, V]]) Fx[And[A, B], V] {
164
-
return FlatMap(e, identity)
165
-
}
166
-
167
-
func AndNest[A, B, V any](e Fx[And[A, B], V]) Fx[A, Fx[B, V]] {
168
-
return Pending(func(a A) Fx[A, Fx[B, V]] { return Const[A](ProvideLeft(e, a)) })
169
-
}
170
-
171
-
func AndCollapse[A, V any](e Fx[And[A, A], V]) Fx[A, V] {
172
-
return Pending(func(a A) Fx[A, V] { return ProvideLeft(e, a) })
173
-
}
174
-
175
-
func ProvideFirstLeft[A, B, C, V any](e Fx[And[And[A, C], B], V], a A) Fx[And[C, B], V] {
176
-
return AndFlat(ProvideLeft(AndNest(e), a))
177
-
}
178
-
179
-
func ProvideFirstRight[A, B, D, V any](e Fx[And[A, And[B, D]], V], b B) Fx[And[A, D], V] {
180
-
return AndSwap(ProvideFirstLeft(AndSwap(e), b))
181
-
}
182
-
183
-
func ProvideFirsts[A, B, C, D, V any](e Fx[And[And[A, C], And[B, D]], V], a A, b B) Fx[And[C, D], V] {
184
-
return ProvideFirstRight(ProvideFirstLeft(e, a), b)
185
-
}
186
-
187
-
func Provide[S, V any](e Fx[S, V], s S) Fx[Nil, V] {
188
-
return ProvideLeft(AndNil(e), s)
189
-
}
190
-
191
-
func ProvideBoth[A, B, V any](e Fx[And[A, B], V], a A, b B) Fx[Nil, V] {
192
-
return Provide(ProvideLeft(e, a), b)
193
-
}
194
-
195
-
func ProvideRight[A, B, V any](e Fx[And[A, B], V], b B) Fx[A, V] {
196
-
return ProvideLeft(AndSwap(e), b)
197
-
}
198
-
199
-
func ProvideLeft[A, B, V any](e Fx[And[A, B], V], a A) Fx[B, V] {
200
-
if e.res != nil {
201
-
return Stop(func() Fx[B, V] { return ProvideLeft(e.res(), a) })
202
-
}
203
-
if e.imm != nil {
204
-
return Const[B](e.imm())
205
-
}
206
-
return Pending(func(b B) Fx[B, V] {
207
-
var ab And[A, B] = func() (A, B) { return a, b }
208
-
var loop func(e Fx[And[A, B], V]) Fx[B, V]
209
-
loop = func(e Fx[And[A, B], V]) Fx[B, V] {
210
-
for {
211
-
e = e.sus(ab)
212
-
if e.res != nil {
213
-
return Stop(func() Fx[B, V] { return loop(e.res()) })
214
-
}
215
-
if e.imm != nil {
216
-
return Const[B](e.imm())
217
-
}
218
-
}
219
-
}
220
-
return loop(e)
221
-
})
222
-
}
223
-
224
-
func Apply[F ~func(I) O, I, O any](i I) Fx[F, O] {
225
-
return Map(Ctx[F](), func(f F) O { return f(i) })
226
-
}
227
-
228
-
func Suspend[A ~func(I) Fx[B, O], B, I, O any](i I) Fx[And[A, B], O] {
229
-
return AndFlat(Apply[A](i))
230
-
}
231
-
232
-
func Handler[A ~func(I) Fx[B, O], B, I, O any](a A) func(Fx[And[A, B], O]) Fx[B, O] {
233
-
return func(e Fx[And[A, B], O]) Fx[B, O] { return ProvideLeft(e, a) }
234
-
}
235
-
236
-
func Handle[F ~func(Fx[And[A, B], O]) Fx[B, O], A ~func(I) Fx[B, O], B, I, O any](i I) Fx[And[F, B], O] {
237
-
return Suspend[F](Suspend[A](i))
238
-
}
239
-
240
-
func Eval[V any](e Fx[Nil, V]) V {
241
-
for {
242
-
if e.res != nil {
243
-
panic("tried to evaluate an stopped effect. try using fx.Resume or fx.Replace on it.")
244
-
}
245
-
if e.imm != nil {
246
-
return e.imm()
247
-
}
248
-
e = e.sus(PNil)
249
-
}
250
-
}
+45
fx/and.go
+45
fx/and.go
···
1
+
package fx
2
+
3
+
type And[A, B any] func() (A, B)
4
+
5
+
func swap[A, B any](ab And[A, B]) And[B, A] {
6
+
var ba And[B, A] = func() (B, A) {
7
+
a, b := ab()
8
+
return b, a
9
+
}
10
+
return ba
11
+
}
12
+
13
+
func left[A, B any](ab And[A, B]) A {
14
+
a, _ := ab()
15
+
return a
16
+
}
17
+
18
+
func right[A, B any](ab And[A, B]) B {
19
+
_, b := ab()
20
+
return b
21
+
}
22
+
23
+
func AndNil[S, V any](e Fx[S, V]) Fx[And[S, Nil], V] {
24
+
return Then[And[S, Nil], V](left, Const)(e)
25
+
}
26
+
27
+
func AndContra[A, B, V any](e Fx[A, V], f func(B) A) Fx[B, V] {
28
+
return ContraMap[V](f)(e)
29
+
}
30
+
31
+
func AndSwap[A, B, V any](e Fx[And[A, B], V]) Fx[And[B, A], V] {
32
+
return Then[And[B, A], V](swap[B, A], Const)(e)
33
+
}
34
+
35
+
func AndFlat[A, B, V any](e Fx[A, Fx[B, V]]) Fx[And[A, B], V] {
36
+
return FlatMap(e, identity)
37
+
}
38
+
39
+
func AndNest[A, B, V any](e Fx[And[A, B], V]) Fx[A, Fx[B, V]] {
40
+
return Pending(func(a A) Fx[A, Fx[B, V]] { return Const[A](ProvideLeft(e, a)) })
41
+
}
42
+
43
+
func AndCollapse[A, V any](e Fx[And[A, A], V]) Fx[A, V] {
44
+
return Pending(func(a A) Fx[A, V] { return ProvideLeft(e, a) })
45
+
}
+49
fx/fx.go
+49
fx/fx.go
···
1
+
package fx
2
+
3
+
type Fx[S, V any] struct {
4
+
// an immediate value
5
+
imm func() V
6
+
// the continuation of a suspended effect
7
+
sus func(S) Fx[S, V]
8
+
// the resume function of an stopped effect
9
+
res func() Fx[S, V]
10
+
}
11
+
12
+
func Pure[V any](v V) FxPure[V] { return Const[Nil](v) }
13
+
14
+
func identity[V any](v V) V { return v }
15
+
16
+
func Const[S, V any](v V) Fx[S, V] { return Fx[S, V]{imm: func() V { return v }} }
17
+
18
+
func Pending[S, V any](f func(S) Fx[S, V]) Fx[S, V] { return Fx[S, V]{sus: f} }
19
+
20
+
func Func[S, V any](f func(S) V) Fx[S, V] {
21
+
return Pending(func(s S) Fx[S, V] { return Const[S](f(s)) })
22
+
}
23
+
24
+
func Ctx[V any]() Fx[V, V] { return Func(identity[V]) }
25
+
26
+
// Continue an effect by transforming its immediate value into another effect.
27
+
func Then[T, U, S, V any](cmap func(T) S, fmap func(V) Fx[T, U]) func(Fx[S, V]) Fx[T, U] {
28
+
return func(e Fx[S, V]) Fx[T, U] {
29
+
if e.res != nil {
30
+
return Stop(func() Fx[T, U] { return Then(cmap, fmap)(e.res()) })
31
+
}
32
+
if e.imm != nil {
33
+
return fmap(e.imm())
34
+
}
35
+
return Pending(func(t T) Fx[T, U] { return Then(cmap, fmap)(e.sus(cmap(t))) })
36
+
}
37
+
}
38
+
39
+
func Eval[V any](e Fx[Nil, V]) V {
40
+
for {
41
+
if e.res != nil {
42
+
panic("tried to evaluate an stopped effect. try using fx.Resume or fx.Replace on it.")
43
+
}
44
+
if e.imm != nil {
45
+
return e.imm()
46
+
}
47
+
e = e.sus(PNil)
48
+
}
49
+
}
+17
fx/handle.go
+17
fx/handle.go
···
1
+
package fx
2
+
3
+
func Apply[F ~func(I) O, I, O any](i I) Fx[F, O] {
4
+
return Map(Ctx[F](), func(f F) O { return f(i) })
5
+
}
6
+
7
+
func Suspend[A ~func(I) Fx[B, O], B, I, O any](i I) Fx[And[A, B], O] {
8
+
return AndFlat(Apply[A](i))
9
+
}
10
+
11
+
func Handler[A ~func(I) Fx[B, O], B, I, O any](a A) func(Fx[And[A, B], O]) Fx[B, O] {
12
+
return func(e Fx[And[A, B], O]) Fx[B, O] { return ProvideLeft(e, a) }
13
+
}
14
+
15
+
func Handle[F ~func(Fx[And[A, B], O]) Fx[B, O], A ~func(I) Fx[B, O], B, I, O any](i I) Fx[And[F, B], O] {
16
+
return Suspend[F](Suspend[A](i))
17
+
}
+39
fx/map.go
+39
fx/map.go
···
1
+
package fx
2
+
3
+
func ContraMap[V, S, R any](f func(R) S) func(Fx[S, V]) Fx[R, V] {
4
+
return func(e Fx[S, V]) Fx[R, V] {
5
+
if e.res != nil {
6
+
return Stop(func() Fx[R, V] { return ContraMap[V](f)(e.res()) })
7
+
}
8
+
if e.imm != nil {
9
+
return Const[R](e.imm())
10
+
}
11
+
return Pending(func(r R) Fx[R, V] {
12
+
return ContraMap[V](f)(e.sus(f(r)))
13
+
})
14
+
}
15
+
}
16
+
17
+
func MapM[S, U, V any](f func(U) Fx[S, V]) func(Fx[S, U]) Fx[S, V] {
18
+
return FlatCont(identity, identity, f)
19
+
}
20
+
21
+
func MapH[S, V, U any](f func(V) U) func(Fx[S, V]) Fx[S, U] {
22
+
return MapM(func(v V) Fx[S, U] { return Const[S](f(v)) })
23
+
}
24
+
25
+
func Map[S, V, U any](e Fx[S, V], f func(V) U) Fx[S, U] {
26
+
return MapH[S](f)(e)
27
+
}
28
+
29
+
func FlatMap[A, U, B, V any](e Fx[A, U], f func(U) Fx[B, V]) Fx[And[A, B], V] {
30
+
return FlatMapH[A](f)(e)
31
+
}
32
+
33
+
func FlatMapH[A, U, B, V any](f func(U) Fx[B, V]) func(Fx[A, U]) Fx[And[A, B], V] {
34
+
return FlatCont[And[A, B]](left, right, f)
35
+
}
36
+
37
+
func FlatCont[N, A, U, B, V any](amap func(N) A, bmap func(N) B, fmap func(U) Fx[B, V]) func(Fx[A, U]) Fx[N, V] {
38
+
return Then(amap, func(u U) Fx[N, V] { return Then(bmap, Const[N, V])(fmap(u)) })
39
+
}
+11
fx/nil.go
+11
fx/nil.go
+50
fx/provide.go
+50
fx/provide.go
···
1
+
package fx
2
+
3
+
func ProvideFirstLeft[A, B, C, V any](e Fx[And[And[A, C], B], V], a A) Fx[And[C, B], V] {
4
+
return AndFlat(ProvideLeft(AndNest(e), a))
5
+
}
6
+
7
+
func ProvideFirstRight[A, B, D, V any](e Fx[And[A, And[B, D]], V], b B) Fx[And[A, D], V] {
8
+
return AndSwap(ProvideFirstLeft(AndSwap(e), b))
9
+
}
10
+
11
+
func ProvideFirsts[A, B, C, D, V any](e Fx[And[And[A, C], And[B, D]], V], a A, b B) Fx[And[C, D], V] {
12
+
return ProvideFirstRight(ProvideFirstLeft(e, a), b)
13
+
}
14
+
15
+
func Provide[S, V any](e Fx[S, V], s S) Fx[Nil, V] {
16
+
return ProvideLeft(AndNil(e), s)
17
+
}
18
+
19
+
func ProvideBoth[A, B, V any](e Fx[And[A, B], V], a A, b B) Fx[Nil, V] {
20
+
return Provide(ProvideLeft(e, a), b)
21
+
}
22
+
23
+
func ProvideRight[A, B, V any](e Fx[And[A, B], V], b B) Fx[A, V] {
24
+
return ProvideLeft(AndSwap(e), b)
25
+
}
26
+
27
+
func ProvideLeft[A, B, V any](e Fx[And[A, B], V], a A) Fx[B, V] {
28
+
if e.res != nil {
29
+
return Stop(func() Fx[B, V] { return ProvideLeft(e.res(), a) })
30
+
}
31
+
if e.imm != nil {
32
+
return Const[B](e.imm())
33
+
}
34
+
return Pending(func(b B) Fx[B, V] {
35
+
var ab And[A, B] = func() (A, B) { return a, b }
36
+
var loop func(e Fx[And[A, B], V]) Fx[B, V]
37
+
loop = func(e Fx[And[A, B], V]) Fx[B, V] {
38
+
for {
39
+
e = e.sus(ab)
40
+
if e.res != nil {
41
+
return Stop(func() Fx[B, V] { return loop(e.res()) })
42
+
}
43
+
if e.imm != nil {
44
+
return Const[B](e.imm())
45
+
}
46
+
}
47
+
}
48
+
return loop(e)
49
+
})
50
+
}
+46
fx/stop.go
+46
fx/stop.go
···
1
+
package fx
2
+
3
+
// Creates an stopped effect from a resume function
4
+
func Stop[S, V any](e func() Fx[S, V]) Fx[S, V] {
5
+
return Fx[S, V]{res: e}
6
+
}
7
+
8
+
// Resume an effect if it was previously stopped.
9
+
func Resume[S, V any](e Fx[S, V]) Fx[S, V] {
10
+
if e.res != nil {
11
+
return e.res()
12
+
}
13
+
if e.imm != nil {
14
+
return Const[S](e.imm())
15
+
}
16
+
return Pending(func(s S) Fx[S, V] { return Resume(e.sus(s)) })
17
+
}
18
+
19
+
// Replace with y if x is already Halted. Otherwise x continues.
20
+
func Replace[S, V any](y func() Fx[S, V]) func(Fx[S, V]) Fx[S, V] {
21
+
return func(x Fx[S, V]) Fx[S, V] {
22
+
if x.res != nil {
23
+
return y()
24
+
}
25
+
if x.imm != nil {
26
+
return Const[S](x.imm())
27
+
}
28
+
return Pending(func(s S) Fx[S, V] { return Replace(y)(x.sus(s)) })
29
+
}
30
+
}
31
+
32
+
// An stopped effect that panics if resumed.
33
+
// Only useful with Replace.
34
+
//
35
+
// For example, an Abort effect halts since it has no possible value for V
36
+
// but then its Handler can Replace the halted effect with an Error value.
37
+
// See: abort/result.go
38
+
func Halt[S, V any]() Fx[S, V] {
39
+
return Stop(func() Fx[S, V] {
40
+
return Fx[S, V]{
41
+
imm: func() V {
42
+
panic("tried to Resume a halted effect. try using Replace instead")
43
+
},
44
+
}
45
+
})
46
+
}
fx_test.go
fx/fx_test.go
fx_test.go
fx/fx_test.go
+1
-1
rw/read.go
+1
-1
rw/read.go
+1
-1
rw/rw_test.go
+1
-1
rw/rw_test.go