{-# LANGUAGE GADTs #-} {-# LANGUAGE PolyKinds #-} {-# LANGUAGE DataKinds #-} {-# LANGUAGE TypeOperators #-} {-# LANGUAGE FlexibleInstances #-} {-# LANGUAGE FlexibleContexts #-} {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE TypeApplications #-} {-# LANGUAGE AllowAmbiguousTypes #-} {-# LANGUAGE RankNTypes #-} {-# LANGUAGE PartialTypeSignatures #-} {-# OPTIONS_GHC -Wno-partial-type-signatures #-} -- | -- Contains main @Enc@ type that carries encoded payload as well as -- @Encoding@ and @Encodings@ types contains encoding functions. -- This module also contains basic combinators for these types. -- -- This module is re-exported in "Data.TypedEncoding" and it is best not to import it directly. module Data.TypedEncoding.Common.Types.Enc where import Data.Proxy import GHC.TypeLits import Data.TypedEncoding.Common.Class.Common import Data.TypedEncoding.Common.Types.Common -- $setup -- >>> :set -XOverloadedStrings -XMultiParamTypeClasses -XDataKinds -XAllowAmbiguousTypes -- >>> import qualified Data.ByteString as B -- >>> import qualified Data.Text as T -- >>> import Data.Functor.Identity -- >>> import Data.TypedEncoding -- >>> import Data.TypedEncoding.Instances.Enc.Base64 () -- >>> import Data.TypedEncoding.Instances.Restriction.BoundedAlphaNums () -- | -- Contains encoded data annotated by -- -- * @nms@ list of @Symbol@s with encoding names (encoding stack) -- * @conf@ that can contain configuration / encoding information such as digest. -- * @str@ the encoded data -- -- Example: -- -- @ -- Enc '["r-ASCII"] () ByteString -- @ -- -- @since 0.1.0.0 data Enc nms conf str where -- | -- @since 0.3.0.0 renamed from MkEnc -- -- Use of this constructor should be kept to a minimum. -- -- Use of 'Data.TypedEncoding.Combinators.Unsafe.unsafeSetPayload' currently recommended -- for recovering 'Enc' from trusted input sources (if avoiding cost of "Data.TypedEncoding.Common.Types.Validation" is important). UnsafeMkEnc :: Proxy nms -> conf -> str -> Enc nms conf str deriving (Show, Eq) -- TODO should Enc be a Functor in conf? -- | -- >>> let disptest = UnsafeMkEnc Proxy () "hello" :: Enc '["TEST"] () T.Text -- >>> displ disptest -- "Enc '[TEST] () (Text hello)" instance (SymbolList xs, Show c, Displ str) => Displ ( Enc xs c str) where displ (UnsafeMkEnc p c s) = "Enc '" ++ displ (Proxy :: Proxy xs) ++ " " ++ show c ++ " " ++ displ s -- | -- @since 0.1.0.0 toEncoding :: conf -> str -> Enc ('[] :: [Symbol]) conf str toEncoding = UnsafeMkEnc Proxy -- | -- @since 0.1.0.0 fromEncoding :: Enc '[] conf str -> str fromEncoding = getPayload -- | -- @since 0.1.0.0 getPayload :: Enc enc conf str -> str getPayload (UnsafeMkEnc _ _ str) = str -- | -- Wraps the encoding function. -- Contains type level information about the encoding name and the algorithm used. -- -- This type is used by programs implementing encoding instance. -- Such program needs to define a value of this type. -- It also implements 'Data.TypedEncoding.Common.Class.Encode.Encode' instance that simply returns that value. -- -- Programs using encoding can access this type using 'Data.TypedEncoding.Common.Class.Encode.Encode.encoding' -- (from the @Encode@ typeclass) but a better (and recommended) approach is to use its plural sibling 'Encodings' -- defined below. -- -- This type has 2 symbol type variables: -- -- * @nm@ defines the encoding -- * @alg@ defines algorithm -- -- These two are related, currently this library only supports -- -- * Names @nm@ containing ":" using format "alg:...", for example name "r-ban:999" has "r-ban" algorithm -- * Names without ":" require that @nm ~ alg@ -- -- Future version are likely to relax this, possibly introducing ability do define more than one algorithm -- for given encoding. -- -- Using 2 variables allows us to define typeclass constraints that work -- with definitions like @"r-ban"@ where @"r-ban:@" can be followed by arbitrary -- string literal. -- -- Examples: -- -- @ -- Encoding (Either EncodeEx) "r-ban:9" "r-ban" () String -- @ -- -- encodes a single character @ <= 9'@ -- -- @ -- Encoding Identity "enc-B64" "enc-B64" () ByteString -- @ -- -- Represents a /Byte 64/ encoder that can operate on any stack of previous encodings. -- (encoding name and algorithm name are "enc-B64", there is no -- additional configuration @()@ needed and it runs in the @Identity@ Functor. -- -- Similar boilerplate for /Decoding/ and /Validation/ is specified in separate modules. -- -- @since 0.3.0.0 data Encoding f (nm :: Symbol) (alg :: Symbol) conf str where -- | Consider this constructor as private or use it with care -- -- Defining constructor like this: -- @ -- MkEncoding :: Proxy nm -> (forall (xs :: [Symbol]) . Enc xs conf str -> f (Enc (nm ': xs) conf str)) -> Encoding f nm (AlgNm nm) conf str -- @ -- -- would make compilation much slower UnsafeMkEncoding :: Proxy nm -> (forall (xs :: [Symbol]) . Enc xs conf str -> f (Enc (nm ': xs) conf str)) -> Encoding f nm alg conf str -- | Type safe smart constructor -- -- Adding the type family @(AlgNm nm)@ mapping to @Encoding@ constructor slows down the compilation. -- Using smart constructor does not have that issue. -- -- This approach also provides more future flexibility with possibility of future overloads relaxing current -- limitations on @alg@ names. -- -- /Notice underscore @_@ convention, it indicates a use of @Algorithm@ @AlgNm@: compiler figures out @alg@ value. These can be slower to compile when used. / -- -- Here are other conventions that relate to the existence of @alg@ -- -- * functions ending with: @'@, for example 'Data.TypedEncoding.Combinators.Encode.encodeF'' have @alg@ -- as first type variable in the @forall@ list. -- -- * functions without tick tend to assume @nm ~ alg@ -- -- This particular function appears to not increase compilation time. -- -- @since 0.3.0.0 _mkEncoding :: forall f (nm :: Symbol) conf str . (forall (xs :: [Symbol]) . Enc xs conf str -> f (Enc (nm ': xs) conf str)) -> Encoding f nm (AlgNm nm) conf str _mkEncoding = UnsafeMkEncoding Proxy -- | -- @since 0.3.0.0 runEncoding' :: forall alg nm f xs conf str . Encoding f nm alg conf str -> Enc xs conf str -> f (Enc (nm ': xs) conf str) runEncoding' (UnsafeMkEncoding _ fn) = fn -- | Same as 'runEncoding'' but compiler figures out algorithm name -- -- Using it can slowdown compilation -- -- This combinator has @Algorithm nm alg@ constraint (which stands for @TakeUntil ":" nm ~ alg@. -- If rules on @alg@ are relaxed this will just return the /default/ algorithm. -- -- If that happens @-XTypeApplications@ annotations will be needed and @_@ methods will simply -- use default algorithm name. -- -- @since 0.3.0.0 _runEncoding :: forall nm f xs conf str alg . (Algorithm nm alg) => Encoding f nm alg conf str -> Enc xs conf str -> f (Enc (nm ': xs) conf str) _runEncoding = runEncoding' @(AlgNm nm) -- | -- HList like construction that defines a list of @Encoding@ elements. -- -- This type is used by programs using / manipulating encodings. -- -- Can be easily accessed with 'Data.TypedEncoding.Common.Class.Encode.EncodeAll' constraint using -- 'Data.TypedEncoding.Common.Class.Encode.EncodeAll.encodings'. But could also be used by creating -- @Encodings@ list by hand. -- -- @since 0.3.0.0 data Encodings f (nms :: [Symbol]) (algs :: [Symbol]) conf str where -- | constructor is to be treated as Unsafe to Encode and Decode instance implementations -- particular encoding instances may expose smart constructors for limited data types ZeroE :: Encodings f '[] '[] conf str ConsE :: Encoding f nm alg conf str -> Encodings f nms algs conf str -> Encodings f (nm ': nms) (alg ': algs) conf str -- | -- Runs encodings, requires -XTypeApplication annotation specifying the algorithm(s) -- -- >>> runEncodings' @'["r-ban"] encodings . toEncoding () $ ("22") :: Either EncodeEx (Enc '["r-ban:111"] () T.Text) -- Left (EncodeEx "r-ban:111" ("Input list has wrong size expecting 3 but length \"22\" == 2")) -- -- @since 0.3.0.0 runEncodings' :: forall algs nms f c str . (Monad f) => Encodings f nms algs c str -> Enc ('[]::[Symbol]) c str -> f (Enc nms c str) runEncodings' ZeroE enc0 = pure enc0 runEncodings' (ConsE fn enc) enc0 = let re :: f (Enc _ c str) = runEncodings' enc enc0 in re >>= runEncoding' fn -- | At a possibly some compilation cost, have compiler figure out algorithm names. -- -- >>> _runEncodings encodings . toEncoding () $ ("Hello World") :: Identity (Enc '["enc-B64","enc-B64"] () B.ByteString) -- Identity (UnsafeMkEnc Proxy () "U0dWc2JHOGdWMjl5YkdRPQ==") -- -- >>> _runEncodings encodings . toEncoding () $ ("22") :: Either EncodeEx (Enc '["r-ban:111"] () T.Text) -- Left (EncodeEx "r-ban:111" ("Input list has wrong size expecting 3 but length \"22\" == 2")) -- -- (see also '_runEncoding') -- @since 0.3.0.0 _runEncodings :: forall nms f c str algs . (Monad f, algs ~ AlgNmMap nms) => Encodings f nms algs c str -> Enc ('[]::[Symbol]) c str -> f (Enc nms c str) _runEncodings = runEncodings' @(AlgNmMap nms)