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Merge pull request #4784 from buzden/effects-tutorial-fix
b0a55aaNiklas Larsson
docs/effects/depeff.rst+16−7
compare with master
unifiedsplit
@@ -153,12 +153,21 @@ file management follows a resource usage protocol with the following
153
153
154- When a file is closed, its handle should no longer be used
154- When a file is closed, its handle should no longer be used
155
155
156−These requirements can be expressed formally in , by creating a
156+These requirements can be expressed formally by creating a
157``FILE_IO`` effect parameterised over a file handle state, which is
157``FILE_IO`` effect parameterised over a file handle state, which is
158either empty, open for reading, or open for writing. The ``FILE_IO``
158either empty, open for reading, or open for writing. The ``FILE_IO``
159−effect’s definition is given below. Note that this
159+effect’s definition is given below.
160+
161+.. note::
160−effect is mainly for illustrative purposes—typically we would also like
162+ This effect is mainly for illustrative purposes.
163+ Typically we would also like to support random access files and
161−to support random access files and better reporting of error conditions.
164+ better reporting of error conditions.
165+
166+ Moreover, the ``FILE`` effect in the ``Effect.File`` module of
167+ the ``effects`` library uses slightly more complicated types to
168+ support erroneous behaviour of each function and to support more
169+ compilcated modes of opening, like for reading **and** writing,
170+ appending or truncating.
162
171
163.. code-block:: idris
172.. code-block:: idris
164
173
@@ -173,7 +182,7 @@ to support random access files and better reporting of error conditions.
173
182
174 open : (fname : String)
183 open : (fname : String)
175 -> (m : Mode)
184 -> (m : Mode)
176− -> Eff Bool [FILE_IO ()]
185+ -> Eff Bool [FILE_IO ()]
177 (\res => [FILE_IO (case res of
186 (\res => [FILE_IO (case res of
178 True => OpenFile m
187 True => OpenFile m
179 False => ())])
188 False => ())])
@@ -191,7 +200,7 @@ In particular, consider the type of ``open``:
191
200
192 open : (fname : String)
201 open : (fname : String)
193 -> (m : Mode)
202 -> (m : Mode)
194− -> Eff Bool [FILE_IO ()]
203+ -> Eff Bool [FILE_IO ()]
195 (\res => [FILE_IO (case res of
204 (\res => [FILE_IO (case res of
196 True => OpenFile m
205 True => OpenFile m
197 False => ())])
206 False => ())])
@@ -207,7 +216,7 @@ we continue the protocol accordingly.
207
216
208 readFile : Eff (List String) [FILE_IO (OpenFile Read)]
217 readFile : Eff (List String) [FILE_IO (OpenFile Read)]
209 readFile = readAcc [] where
218 readFile = readAcc [] where
210− readAcc : List String -> Eff (List String) [FILE_IO (OpenFile Read)]
219+ readAcc : List String -> Eff (List String) [FILE_IO (OpenFile Read)]
211 readAcc acc = if (not !eof)
220 readAcc acc = if (not !eof)
212 then readAcc (!readLine :: acc)
221 then readAcc (!readLine :: acc)
213 else pure (reverse acc)
222 else pure (reverse acc)
docs/effects/summary.rst+23−23
@@ -43,16 +43,16 @@ FILE\_IO
43 data OpenFile : Mode -> Type
43 data OpenFile : Mode -> Type
44
44
45 open : (fname : String)
45 open : (fname : String)
46− -> (m : Mode)
46+ -> (m : Mode)
47− -> Eff Bool [FILE_IO ()]
47+ -> Eff Bool [FILE_IO ()]
48− (\res => [FILE_IO (case res of
48+ (\res => [FILE_IO (case res of
49− True => OpenFile m
49+ True => OpenFile m
50− False => ())])
50+ False => ())])
51 close : Eff () [FILE_IO (OpenFile m)] [FILE_IO ()]
51 close : Eff () [FILE_IO (OpenFile m)] [FILE_IO ()]
52
52
53− readLine : Eff String [FILE_IO (OpenFile Read)]
53+ readLine : Eff String [FILE_IO (OpenFile Read)]
54 writeLine : String -> Eff () [FILE_IO (OpenFile Write)]
54 writeLine : String -> Eff () [FILE_IO (OpenFile Write)]
55− eof : Eff Bool [FILE_IO (OpenFile Read)]
55+ eof : Eff Bool [FILE_IO (OpenFile Read)]
56
56
57 Handler FileIO IO where { ... }
57 Handler FileIO IO where { ... }
58
58
@@ -69,9 +69,9 @@ RND
69
69
70 RND : EFFECT
70 RND : EFFECT
71
71
72− srand : Integer -> Eff m () [RND]
72+ srand : Integer -> Eff () [RND]
73− rndInt : Integer -> Integer -> Eff m Integer [RND]
73+ rndInt : Integer -> Integer -> Eff Integer [RND]
74− rndFin : (k : Nat) -> Eff m (Fin (S k)) [RND]
74+ rndFin : (k : Nat) -> Eff (Fin (S k)) [RND]
75
75
76 Handler Random m where { ... }
76 Handler Random m where { ... }
77
77
@@ -86,7 +86,7 @@ SELECT
86
86
87 SELECT : EFFECT
87 SELECT : EFFECT
88
88
89− select : List a -> Eff m a [SELECT]
89+ select : List a -> Eff a [SELECT]
90
90
91 Handler Selection Maybe where { ... }
91 Handler Selection Maybe where { ... }
92 Handler Selection List where { ... }
92 Handler Selection List where { ... }
@@ -102,10 +102,10 @@ STATE
102
102
103 STATE : Type -> EFFECT
103 STATE : Type -> EFFECT
104
104
105− get : Eff m x [STATE x]
105+ get : Eff x [STATE x]
106− put : x -> Eff m () [STATE x]
106+ put : x -> Eff () [STATE x]
107− putM : y -> Eff m () [STATE x] [STATE y]
107+ putM : y -> Eff () [STATE x] [STATE y]
108− update : (x -> x) -> Eff m () [STATE x]
108+ update : (x -> x) -> Eff () [STATE x]
109
109
110 Handler State m where { ... }
110 Handler State m where { ... }
111
111
@@ -121,12 +121,12 @@ STDIO
121
121
122 STDIO : EFFECT
122 STDIO : EFFECT
123
123
124− putChar : Handler StdIO m => Char -> Eff m () [STDIO]
124+ putChar : Char -> Eff () [STDIO]
125− putStr : Handler StdIO m => String -> Eff m () [STDIO]
125+ putStr : String -> Eff () [STDIO]
126− putStrLn : Handler StdIO m => String -> Eff m () [STDIO]
126+ putStrLn : String -> Eff () [STDIO]
127
127
128− getStr : Handler StdIO m => Eff m String [STDIO]
128+ getStr : Eff String [STDIO]
129− getChar : Handler StdIO m => Eff m Char [STDIO]
129+ getChar : Eff Char [STDIO]
130
130
131 Handler StdIO IO where { ... }
131 Handler StdIO IO where { ... }
132 Handler StdIO (IOExcept a) where { ... }
132 Handler StdIO (IOExcept a) where { ... }
@@ -144,9 +144,9 @@ SYSTEM
144
144
145 SYSTEM : EFFECT
145 SYSTEM : EFFECT
146
146
147− getArgs : Handler System e => Eff e (List String) [SYSTEM]
147+ getArgs : Eff (List String) [SYSTEM]
148− time : Handler System e => Eff e Int [SYSTEM]
148+ time : Eff Int [SYSTEM]
149− getEnv : Handler System e => String -> Eff e (Maybe String) [SYSTEM]
149+ getEnv : String -> Eff (Maybe String) [SYSTEM]
150
150
151 Handler System IO where { ... }
151 Handler System IO where { ... }
152 Handler System (IOExcept a) where { ... }
152 Handler System (IOExcept a) where { ... }