configuration-tools 0.2.1 → 0.2.2

raw patch · 8 files changed

+240/−109 lines, 8 filesPVP: major bump suggested

API removals or changes: PVP suggests a major version bump

API changes (from Hackage documentation)

Files

• CHANGELOG.md +14/−0
• README.md +32/−18
• configuration-tools.cabal +2/−2
• constraints +24/−21
• examples/Example.hs +14/−15
• src/Configuration/Utils.hs +122/−26
• src/Configuration/Utils/Http.hs +24/−24
• src/Configuration/Utils/Internal.hs +8/−3

@@ -1,3 +1,17 @@+0.2.2+=====++*   Add Lens `piOptionParserAndDefaultConfiguration` that gives simultaneous+    accesses to `piOptionParser` and `piDefaultConfiguration` which allows+    changing the type parameter of `ProgramInfo a`.++*   Introduce function `setProperty`. It is used as the `..:` operator+    but allows to specify a custom parser for the property value instead+    of the default `parseJSON` from the `FromJSON` instance.++*   Introduce operators `(<*<)`, `(>*>)`, `(<$<)`, `(>$>)` and deprecate+    `(⊙)` and `(<.>)`.+ 0.2.1 ===== 

@@ -12,10 +12,25 @@ The main features are  1.   configuration management through integration of command line option-     parsing and configuration files and+     parsing and configuration files, 2.   a `Setup.hs` file that generates a `PkgInfo` module for each component-     of a package that provide information about the package and the build.+     of a package that provide information about the package and the build, and+3.   a set of types for configuration of HTTP services and clients along+     with aeson instances and command line option parsers. +The ultimate goal for this package is a general framework for+compositional configuration management for software components.+Instead of designing such a framework from scratch the approach of this+package is to first explore design and implementation patterns based+on practical examples and by gluing together existing technology.++Therefor at the current state this package mostly provides operators and+coding patterns for writing stylish boilerplate code.++Once we feel that the developed patterns cover a sufficient portion of+real world requirements we plan to rewrite this package such that+the boilerplate is hidden behind a clean and simple DSL.+ Configuration Management ======================== @@ -119,16 +134,16 @@  Now we define an [aeson](https://hackage.haskell.org/package/aeson) `FromJSON` instance that yields a function that updates a given `Auth` value with the-values from the parsed JSON value. The `<.>` operator is functional composition+values from the parsed JSON value. The `<*<` operator is functional composition lifted for applicative functors and `%` is a version of `$` with a different precedence that helps to reduce the use of paranthesis in applicative style code.  ~~~{.haskell} instance FromJSON (Auth -> Auth) where-    parseJSON = withObject "Auth" $ \o -> pure id-        <.> user ..: "user" % o-        <.> pwd ..: "pwd" % o+    parseJSON = withObject "Auth" $ \o -> id+        <$< user ..: "user" % o+        <*< pwd ..: "pwd" % o ~~~  The `ToJSON` instance is needed to print the configuration (as YAML document)@@ -150,11 +165,11 @@  ~~~{.haskell} pAuth :: MParser Auth-pAuth = pure id-    <.> user .:: strOption+pAuth = id+    <$< user .:: strOption         % long "user"         <> help "user name"-    <.> pwd .:: strOption+    <*< pwd .:: strOption         % long "pwd"         <> help "password for user" ~~~@@ -192,10 +207,10 @@     }  instance FromJSON (HttpURL -> HttpURL) where-    parseJSON = withObject "HttpURL" $ \o -> pure id-        <.> auth %.: "auth" % o-        <.> domain ..: "domain" % o-        <.> path ..: "path" % o+    parseJSON = withObject "HttpURL" $ \o -> id+        <$< auth %.: "auth" % o+        <*< domain ..: "domain" % o+        <*< path ..: "path" % o  instance ToJSON HttpURL where     toJSON a = object@@ -205,15 +220,14 @@         ]  pHttpURL :: MParser HttpURL-pHttpURL = pure id-    <.> auth %:: pAuth-    <.> domain .:: strOption+pHttpURL = id+    <$< auth %:: pAuth+    <*< domain .:: strOption         % long "domain"         <> short 'd'         <> help "HTTP domain"-    <.> path .:: strOption+    <*< path .:: strOption         % long "path"-        <> short 'p'         <> help "HTTP URL path" ~~~ 

@@ -3,7 +3,7 @@ -- ------------------------------------------------------ --  Name:                configuration-tools-Version:             0.2.1+Version:             0.2.2 Synopsis:            Tools for specifying and parsing configurations description:     Tools for specifying and parsing configurations@@ -53,7 +53,7 @@ source-repository this     type: git     location: https://github.com/alephcloud/hs-configuration-tools.git-    tag: 0.2.1+    tag: 0.2.2  Library     hs-source-dirs: src

@@ -1,36 +1,39 @@-constraints: Cabal ==1.21.0.0,+constraints: Cabal ==1.20.0.1,              MonadRandom ==0.1.13,              aeson ==0.7.0.6,              ansi-terminal ==0.6.1.1,              ansi-wl-pprint ==0.6.7.1,              array ==0.5.0.0,-             attoparsec ==0.11.3.4,-             base ==4.7.0.0,+             attoparsec ==0.12.1.0,+             base ==4.7.0.1,              base-unicode-symbols ==0.2.2.4,+             bifunctors ==4.1.1.1,              bytestring ==0.10.4.0,              comonad ==4.2,-             conduit ==1.1.2.1,-             configuration-tools ==0.2,+             conduit ==1.1.6,+             configuration-tools ==0.2.2,              containers ==0.5.5.1,-             contravariant ==0.5.1,+             contravariant ==0.6,              deepseq ==1.3.0.2,              directory ==1.2.1.0,-             distributive ==0.4.3.2,-             dlist ==0.7.0.1,-             either ==4.1.2,+             distributive ==0.4.4,+             dlist ==0.7.1,+             either ==4.3.0.1,              errors ==1.4.7,              exceptions ==0.6.1,              filepath ==1.3.0.2,+             free ==4.9,              ghc-prim ==0.3.1.0,              hashable ==1.2.2.0,              integer-gmp ==0.5.1.0,-             lifted-base ==0.2.2.2,+             lifted-base ==0.2.3.0,              mmorph ==1.0.3,              monad-control ==0.3.3.0,              mtl ==2.1.3.1,              nats ==0.2,              old-locale ==1.0.0.6,-             optparse-applicative ==0.8.1,+             optparse-applicative ==0.9.0,+             prelude-extras ==0.4,              pretty ==1.1.1.1,              primitive ==0.5.3.0,              process ==1.2.0.0,@@ -38,20 +41,20 @@              random ==1.0.1.1,              resourcet ==1.1.2.2,              rts ==1.0,-             safe ==0.3.4,-             scientific ==0.3.2.0,-             semigroupoids ==4.0.2,-             semigroups ==0.14,-             syb ==0.4.1,+             safe ==0.3.6,+             scientific ==0.3.3.0,+             semigroupoids ==4.0.2.1,+             semigroups ==0.15.1,+             syb ==0.4.2,              tagged ==0.7.2,              template-haskell ==2.9.0.0,-             text ==1.1.1.2,+             text ==1.1.1.3,              time ==1.4.2,              transformers ==0.3.0.0,              transformers-base ==0.4.2,-             transformers-compat ==0.1.1.1,+             transformers-compat ==0.3.3.4,              unix ==2.7.0.1,-             unordered-containers ==0.2.4.0,-             vector ==0.10.9.1,+             unordered-containers ==0.2.5.0,+             vector ==0.10.11.0,              void ==0.6.1,-             yaml ==0.8.8.3+             yaml ==0.8.8.4

@@ -43,9 +43,9 @@     }  instance FromJSON (Auth → Auth) where-    parseJSON = withObject "Auth" $ \o → pure id-        ⊙ user ..: "user" × o-        ⊙ pwd ..: "pwd" × o+    parseJSON = withObject "Auth" $ \o → id+        <$< user ..: "user" × o+        <*< pwd ..: "pwd" × o  instance ToJSON Auth where     toJSON a = object@@ -54,11 +54,11 @@         ]  pAuth ∷ MParser Auth-pAuth = pure id-    ⊙ user .:: strOption+pAuth = id+    <$< user .:: strOption         × long "user"         ⊕ help "user name"-    ⊙ pwd .:: strOption+    <*< pwd .:: strOption         × long "pwd"         ⊕ help "password for user" @@ -87,10 +87,10 @@     }  instance FromJSON (HttpURL → HttpURL) where-    parseJSON = withObject "HttpURL" $ \o → pure id-        ⊙ auth %.: "auth" × o-        ⊙ domain ..: "domain" × o-        ⊙ path ..: "path" × o+    parseJSON = withObject "HttpURL" $ \o → id+        <$< auth %.: "auth" × o+        <*< domain ..: "domain" × o+        <*< path ..: "path" × o  instance ToJSON HttpURL where     toJSON a = object@@ -100,15 +100,14 @@         ]  pHttpURL ∷ MParser HttpURL-pHttpURL = pure id-    ⊙ auth %:: pAuth-    ⊙ domain .:: strOption+pHttpURL = id+    <$< auth %:: pAuth+    <*< domain .:: strOption         × long "domain"         ⊕ short 'd'         ⊕ help "HTTP domain"-    ⊙ path .:: strOption+    <*< path .:: strOption         × long "path"-        ⊕ short 'p'         ⊕ help "HTTP URL path"  -- | Information about the main Application

@@ -55,6 +55,7 @@ , piHelpFooter , piOptionParser , piDefaultConfiguration+, piOptionParserAndDefaultConfiguration  -- * Running an Configured Application , runWithConfiguration@@ -67,16 +68,22 @@ , (%::)  -- * Parsing of Configuration Files with Default Values+, setProperty , (..:) , (%.:)  -- * Misc Utils , (%) , (×)+, (<*<)+, (>*>)+, (<$<)+, (>$>) , (<.>) , (⊙) , dropAndUncaml , Lens'+, Lens  -- * Configuration of Optional Values -- $maybe@@ -140,13 +147,45 @@  -- | Functional composition for applicative functors. --+(<*<) ∷ Applicative φ ⇒ φ (β → γ) → φ (α → β) → φ (α → γ)+(<*<) a b = pure (.) <*> a <*> b+infixr 4 <*<+{-# INLINE (<*<) #-}++-- | Functional composition for applicative functors with its arguments+-- flipped.+--+(>*>) ∷ Applicative φ ⇒ φ (α → β) → φ (β → γ) → φ (α → γ)+(>*>) = flip (<*<)+infixr 4 >*>+{-# INLINE (>*>) #-}++-- | Applicative functional composition between a pure function+-- and an applicative function.+--+(<$<) ∷ Functor φ ⇒ (β → γ) → φ (α → β) → φ (α → γ)+(<$<) a b = (a .) <$> b+infixr 4 <$<+{-# INLINE (<$<) #-}++-- | Applicative functional composition between a pure function+-- and an applicative function with its arguments flipped.+--+(>$>) ∷ Functor φ ⇒ φ (α → β) → (β → γ) → φ (α → γ)+(>$>) = flip (<$<)+infixr 4 >$>+{-# INLINE (>$>) #-}++-- | Functional composition for applicative functors.+-- -- This is a rather popular operator. Due to conflicts (for instance with the -- lens package) it may have to be imported qualified. -- (<.>) ∷ Applicative φ ⇒ φ (β → γ) → φ (α → β) → φ (α → γ)-(<.>) a b = pure (.) <*> a <*> b+(<.>) = (<*<) infixr 4 <.> {-# INLINE (<.>) #-}+{-# DEPRECATED (<.>) "use '<*<' instead" #-}  -- | For people who like nicely aligned code and do not mind messing with -- editor key-maps: here a version of '<.>' that uses a unicode symbol@@ -161,6 +200,7 @@ (⊙) = (<.>) infixr 4 ⊙ {-# INLINE (⊙) #-}+{-# DEPRECATED (⊙) "use '<*<' instead" #-}  -- -------------------------------------------------------------------------- -- -- Applicative Option Parsing with Default Values@@ -184,14 +224,13 @@ -- > -- $(makeLenses ''Auth) -- > -- > pAuth ∷ MParser Auth--- > pAuth = pure id--- >    ⊙ user .:: strOption+-- > pAuth = id+-- >    <$< user .:: strOption -- >        × long "user" -- >        ⊕ short 'u' -- >        ⊕ help "user name"--- >    ⊙ pwd .:: strOption+-- >    <*< pwd .:: strOption -- >        × long "pwd"--- >        ⊕ short 'p' -- >        ⊕ help "password for user" -- (.::) ∷ (Alternative φ, Applicative φ) ⇒ Lens' α β → φ β → φ (α → α)@@ -222,9 +261,9 @@ -- > -- $(makeLenses ''HttpURL) -- > -- > pHttpURL ∷ MParser HttpURL--- > pHttpURL = pure id--- >     ⊙ auth %:: pAuth--- >     ⊙ domain .:: strOption+-- > pHttpURL = id+-- >     <$< auth %:: pAuth+-- >     <*< domain .:: strOption -- >         × long "domain" -- >         ⊕ short 'd' -- >         ⊕ help "HTTP domain"@@ -247,10 +286,48 @@     | otherwise = let (h:t) = drop i l         in toLower h : concatMap (\x → if isUpper x then "-" ⊕ [toLower x] else [x]) t --- | A variant of the aeson operator '.:' that creates a parser--- that updates a setter with the parsed value.+-- | A JSON 'Value' parser for a property of a given+-- 'Object' that updates a setter with the parsed value. -- -- > data Auth = Auth+-- >     { _userId ∷ !Int+-- >     , _pwd ∷ !String+-- >     }+-- >+-- > userId ∷ Functor φ ⇒ (Int → φ Int) → Auth → φ Auth+-- > userId f s = (\u → s { _userId = u }) <$> f (_userId s)+-- >+-- > pwd ∷ Functor φ ⇒ (String → φ String) → Auth → φ Auth+-- > pwd f s = (\p → s { _pwd = p }) <$> f (_pwd s)+-- >+-- > -- or with lenses and TemplateHaskell just:+-- > -- $(makeLenses ''Auth)+-- >+-- > instance FromJSON (Auth → Auth) where+-- >     parseJSON = withObject "Auth" $ \o → id+-- >         <$< setProperty user "user" p o+-- >         <*< setProperty pwd "pwd" parseJSON o+-- >       where+-- >         p = withText "user" $ \case+-- >             "alice" → pure (0 ∷ Int)+-- >             "bob" → pure 1+-- >             e → faile $ "unrecognized user " ⊕ e+--+setProperty+    ∷ Lens' α β -- ^ Lens that into the target that is updated by the parser+    → T.Text -- ^ the JSON property name+    → (Value → Parser β) -- ^ the JSON 'Value' parser that is used to parse the value of the property+    → Object -- ^ the parsed JSON 'Value' 'Object'+    → Parser (α → α)+setProperty s k p o = case H.lookup k o of+    Nothing → pure id+    Just v → set s <$> p v++-- | A variant of the 'setProperty' that uses the default 'parseJSON' method from the+-- 'FromJSON' instance to parse the value of the property. Its usage pattern mimics the+-- usage pattern of the '.:' operator from the aeson library.+--+-- > data Auth = Auth -- >     { _user ∷ !String -- >     , _pwd ∷ !String -- >     }@@ -265,14 +342,12 @@ -- > -- $(makeLenses ''Auth) -- > -- > instance FromJSON (Auth → Auth) where--- >     parseJSON = withObject "Auth" $ \o → pure id--- >         ⊙ user ..: "user" × o--- >         ⊙ pwd ..: "pwd" × o+-- >     parseJSON = withObject "Auth" $ \o → id+-- >         <$< user ..: "user" × o+-- >         <*< pwd ..: "pwd" × o -- (..:) ∷ FromJSON β ⇒ Lens' α β → T.Text → Object → Parser (α → α)-(..:) s k o = case H.lookup k o of-    Nothing → pure id-    Just v → set s <$> parseJSON v+(..:) s k = setProperty s k parseJSON infix 6 ..: {-# INLINE (..:) #-} @@ -297,9 +372,9 @@ -- > -- $(makeLenses ''HttpURL) -- > -- > instance FromJSON (HttpURL → HttpURL) where--- >     parseJSON = withObject "HttpURL" $ \o → pure id--- >         ⊙ auth %.: "auth" × o--- >         ⊙ domain ..: "domain" × o+-- >     parseJSON = withObject "HttpURL" $ \o → id+-- >         <$< auth %.: "auth" × o+-- >         <*< domain ..: "domain" × o -- (%.:) ∷ FromJSON (β → β) ⇒ Lens' α β → T.Text → Object → Parser (α → α) (%.:) s k o = case H.lookup k o of@@ -327,28 +402,49 @@ -- | Program Description -- piDescription ∷ Lens' (ProgramInfo α) String-piDescription = lens _piDescription $ \s a → s { _piDescription = a}+piDescription = lens _piDescription $ \s a → s { _piDescription = a }+{-# INLINE piDescription #-}  -- | Help header -- piHelpHeader ∷ Lens' (ProgramInfo α) (Maybe String)-piHelpHeader = lens _piHelpHeader $ \s a → s { _piHelpHeader = a}+piHelpHeader = lens _piHelpHeader $ \s a → s { _piHelpHeader = a }+{-# INLINE piHelpHeader #-}  -- | Help footer -- piHelpFooter ∷ Lens' (ProgramInfo α) (Maybe String)-piHelpFooter = lens _piHelpFooter $ \s a → s { _piHelpFooter = a}+piHelpFooter = lens _piHelpFooter $ \s a → s { _piHelpFooter = a }+{-# INLINE piHelpFooter #-}  -- | options parser for configuration (TODO consider using a typeclass for this) -- piOptionParser ∷ Lens' (ProgramInfo α) (MParser α)-piOptionParser = lens _piOptionParser $ \s a → s { _piOptionParser = a}+piOptionParser = lens _piOptionParser $ \s a → s { _piOptionParser = a }+{-# INLINE piOptionParser #-}  -- | default configuration -- piDefaultConfiguration ∷ Lens' (ProgramInfo α) α-piDefaultConfiguration = lens _piDefaultConfiguration $ \s a → s { _piDefaultConfiguration = a}+piDefaultConfiguration = lens _piDefaultConfiguration $ \s a → s { _piDefaultConfiguration = a }+{-# INLINE piDefaultConfiguration #-} +-- | 'Lens' for simultaneous query and update of 'piOptionParser' and+-- 'piDefaultConfiguration'. This supports to change the type of 'ProgramInfo'+-- with 'over' and 'set'.+--+piOptionParserAndDefaultConfiguration ∷ Lens (ProgramInfo α) (ProgramInfo β) (MParser α, α) (MParser β, β)+piOptionParserAndDefaultConfiguration = lens g $ \s (a,b) → ProgramInfo+    { _piDescription = _piDescription s+    , _piHelpHeader = _piHelpHeader s+    , _piHelpFooter = _piHelpFooter s+    , _piOptionParser = a+    , _piDefaultConfiguration = b+    }+  where+    g s = (_piOptionParser s, _piDefaultConfiguration s)+{-# INLINE piOptionParserAndDefaultConfiguration #-}+ -- | Smart constructor for 'ProgramInfo'. -- -- 'piHelpHeader' and 'piHelpFooter' are set to 'Nothing'.@@ -544,7 +640,7 @@ -- -- For this the following orphan 'FromJSON' instance is provided: ----- > instance (FromJSON (a -> a), FromJSON a) => FromJSON (Maybe a -> Maybe a)+-- > instance (FromJSON (a → a), FromJSON a) ⇒ FromJSON (Maybe a → Maybe a) -- >     parseJSON Null = pure (const Nothing) -- >     parseJSON v = f <$> parseJSON v <*> parseJSON v -- >       where@@ -580,7 +676,7 @@ -- default value that is given to the configuration parser is 'Nothing' and the -- parsed configuration is not 'Null'. ---instance (FromJSON (a -> a), FromJSON a) => FromJSON (Maybe a -> Maybe a) where+instance (FromJSON (a → a), FromJSON a) ⇒ FromJSON (Maybe a → Maybe a) where      -- | If the configuration explicitly requires 'Null' the result     -- is 'Nothing'.

@@ -69,9 +69,9 @@     }  instance FromJSON (HttpServiceTLSConfiguration → HttpServiceTLSConfiguration) where-    parseJSON = withObject "HttpServiceTLSConfiguration" $ \o → pure id-        ⊙ hstcCertFile ..: "cert-file" × o-        ⊙ hstcKeyFile ..: "pem-file" × o+    parseJSON = withObject "HttpServiceTLSConfiguration" $ \o → id+        <$< hstcCertFile ..: "cert-file" × o+        <*< hstcKeyFile ..: "pem-file" × o  -- | This is used as default when wrapped into Maybe and --@@ -96,11 +96,11 @@ -- provided even though TLS is turned off. -- pHttpServiceTLSConfiguration ∷ String → MParser HttpServiceTLSConfiguration-pHttpServiceTLSConfiguration prefix = pure id-    ⊙ hstcCertFile .:: strOption+pHttpServiceTLSConfiguration prefix = id+    <$< hstcCertFile .:: strOption         × long (prefix ⊕ "cert-file")         ⊕ help "File with PEM encoded TLS Certificate"-    ⊙ hstcKeyFile .:: strOption+    <*< hstcKeyFile .:: strOption         × long (prefix ⊕ "key-file")         ⊕ help "File with PEM encoded TLS key" @@ -145,11 +145,11 @@     }  instance FromJSON (HttpServiceConfiguration → HttpServiceConfiguration) where-    parseJSON = withObject "HttpServiceConfiguration" $ \o → pure id-        ⊙ hscHost ∘ bs ..: "host" × o-        ⊙ hscPort ..: "port" × o-        ⊙ hscInterface ∘ bs ..: "interface" × o-        ⊙ hscUseTLS %.: "use-tls" × o+    parseJSON = withObject "HttpServiceConfiguration" $ \o → id+        <$< hscHost ∘ bs ..: "host" × o+        <*< hscPort ..: "port" × o+        <*< hscInterface ∘ bs ..: "interface" × o+        <*< hscUseTLS %.: "use-tls" × o       where         bs ∷ Iso' B8.ByteString String         bs = iso B8.unpack B8.pack@@ -163,17 +163,17 @@         ]  pHttpServiceConfiguration ∷ String → MParser HttpServiceConfiguration-pHttpServiceConfiguration prefix = pure id-    ⊙ hscHost ∘ bs .:: strOption+pHttpServiceConfiguration prefix = id+    <$< hscHost ∘ bs .:: strOption         × long (prefix ⊕ "host")         ⊕ help "Hostname of the service"-    ⊙ hscPort .:: option+    <*< hscPort .:: option         × long (prefix ⊕ "port")         ⊕ help "Port of the service"-    ⊙ hscInterface ∘ bs .:: option+    <*< hscInterface ∘ bs .:: option         × long (prefix ⊕ "interface")         ⊕ help "Interface of the service"-    ⊙ (hscUseTLS %:: (fmap <$> pHttpServiceTLSConfiguration prefix))+    <*< (hscUseTLS %:: (fmap <$> pHttpServiceTLSConfiguration prefix))   where     bs ∷ Iso' B8.ByteString String     bs = iso B8.unpack B8.pack@@ -205,10 +205,10 @@     }  instance FromJSON (HttpClientConfiguration → HttpClientConfiguration) where-    parseJSON = withObject "HttpClientConfiguration" $ \o → pure id-        ⊙ hccHost ∘ bs ..: "host" × o-        ⊙ hccPort ..: "port" × o-        ⊙ hccUseTLS ..: "use-tls" × o+    parseJSON = withObject "HttpClientConfiguration" $ \o → id+        <$< hccHost ∘ bs ..: "host" × o+        <*< hccPort ..: "port" × o+        <*< hccUseTLS ..: "use-tls" × o       where         bs ∷ Iso' B8.ByteString String         bs = iso B8.unpack B8.pack@@ -221,14 +221,14 @@         ]  pHttpClientConfiguration ∷ String → MParser HttpClientConfiguration-pHttpClientConfiguration serviceName = pure id-    ⊙ hccHost ∘ bs .:: strOption+pHttpClientConfiguration serviceName = id+    <$< hccHost ∘ bs .:: strOption         × long (serviceName ⊕ "-host")         ⊕ help ("Hostname of " ⊕ serviceName)-    ⊙ hccPort .:: option+    <*< hccPort .:: option         × long (serviceName ⊕ "-port")         ⊕ help ("Port of " ⊕ serviceName)-    ⊙ hccUseTLS .:: switch+    <*< hccUseTLS .:: switch         × long (serviceName ⊕ "-use-tls")         ⊕ help ("Connect to " ⊕ serviceName ⊕ " via TLS")   where

@@ -11,6 +11,7 @@ , over , set , Lens'+, Lens , Iso' , iso ) where@@ -27,9 +28,13 @@  -- | This is the same type as the type from the lens library with the same name. ---type Lens' β α = Functor φ ⇒ (α → φ α) → β → φ β+type Lens σ τ α β = Functor φ ⇒ (α → φ β) → σ → φ τ -lens ∷ Functor φ ⇒ (β → α) → (β → α → β) → (α → φ α) → β → φ β+-- | This is the same type as the type from the lens library with the same name.+--+type Lens' σ α = Lens σ σ α α++lens ∷ (σ → α) → (σ → β → τ) → Lens σ τ α β lens getter setter lGetter s = setter s `fmap` lGetter (getter s)  over ∷ ((α → Identity α) → β → Identity β) → (α → α) → β → β@@ -42,5 +47,5 @@ -- type Iso' β α = (Profunctor π, Functor φ) ⇒ π α (φ α) → π β (φ β) -iso :: (β -> α) -> (α -> β) -> Iso' β α+iso ∷ (β → α) → (α → β) → Iso' β α iso f g = dimap f (fmap g)