Safe Haskell	None
Language	GHC2021

KDL.Decoder.Internal.Decoder

Contents

Decoder
DecodeArrow
DecodeStateM
DecodeState

Synopsis

type Decoder o a = DecodeArrow o () a
data DecodeArrow o a b = DecodeArrow {
- schema :: SchemaOf o
- run :: a -> DecodeStateM o b
}
liftDecodeM :: (a -> DecodeM b) -> DecodeArrow o a b
withDecoder :: DecodeArrow o a b -> (b -> DecodeM c) -> DecodeArrow o a c
fail :: forall b o. DecodeArrow o Text b
debug :: Show o => DecodeArrow o a ()
type DecodeStateM o a = StateT (DecodeState o) DecodeM a
runDecodeStateM :: o -> DecodeHistory o -> DecodeStateM o a -> DecodeM a
class HasDecodeHistory (o :: k) where
- data DecodeHistory (o :: k)
- emptyDecodeHistory :: DecodeHistory o
data family DecodeHistory (o :: k)
data DecodeState o = DecodeState {
- object :: !o
- history :: DecodeHistory o
}

Decoder

type Decoder o a = DecodeArrow o () a Source #

DecodeArrow

data DecodeArrow o a b Source #

DecodeArrow o a b represents an arrow with input a and output b, within the context of decoding a KDL object of type o. It also knows the expected schema of o. Most of the time, a is (); it would only be different if you're using Arrows notation.

We're using arrows here so that we can:

Get the schema without running the decoder, and also
Use previously decoded values to inform decoding other values

Using monads alone would lose (1), but applicatives can't do (2).

Constructors

DecodeArrow
Fields schema :: SchemaOf o run :: a -> DecodeStateM o b

Instances

Instances details

Category (DecodeArrow o :: Type -> Type -> Type) Source #
Instance details Defined in KDL.Decoder.Internal.Decoder Methods id :: DecodeArrow o a a # (.) :: DecodeArrow o b c -> DecodeArrow o a b -> DecodeArrow o a c #
Arrow (DecodeArrow o) Source #
Instance details Defined in KDL.Decoder.Internal.Decoder Methods arr :: (b -> c) -> DecodeArrow o b c # first :: DecodeArrow o b c -> DecodeArrow o (b, d) (c, d) # second :: DecodeArrow o b c -> DecodeArrow o (d, b) (d, c) # (***) :: DecodeArrow o b c -> DecodeArrow o b' c' -> DecodeArrow o (b, b') (c, c') # (&&&) :: DecodeArrow o b c -> DecodeArrow o b c' -> DecodeArrow o b (c, c') #
ArrowChoice (DecodeArrow o) Source #
Instance details Defined in KDL.Decoder.Internal.Decoder Methods left :: DecodeArrow o b c -> DecodeArrow o (Either b d) (Either c d) # right :: DecodeArrow o b c -> DecodeArrow o (Either d b) (Either d c) # (+++) :: DecodeArrow o b c -> DecodeArrow o b' c' -> DecodeArrow o (Either b b') (Either c c') # (\|\|\|) :: DecodeArrow o b d -> DecodeArrow o c d -> DecodeArrow o (Either b c) d #
Alternative (DecodeArrow o a) Source #
Instance details Defined in KDL.Decoder.Internal.Decoder Methods empty :: DecodeArrow o a a0 # (<\|>) :: DecodeArrow o a a0 -> DecodeArrow o a a0 -> DecodeArrow o a a0 # some :: DecodeArrow o a a0 -> DecodeArrow o a [a0] # many :: DecodeArrow o a a0 -> DecodeArrow o a [a0] #
Applicative (DecodeArrow o a) Source #
Instance details Defined in KDL.Decoder.Internal.Decoder Methods pure :: a0 -> DecodeArrow o a a0 # (<>) :: DecodeArrow o a (a0 -> b) -> DecodeArrow o a a0 -> DecodeArrow o a b # liftA2 :: (a0 -> b -> c) -> DecodeArrow o a a0 -> DecodeArrow o a b -> DecodeArrow o a c # (>) :: DecodeArrow o a a0 -> DecodeArrow o a b -> DecodeArrow o a b # (<*) :: DecodeArrow o a a0 -> DecodeArrow o a b -> DecodeArrow o a a0 #
Functor (DecodeArrow o a) Source #
Instance details Defined in KDL.Decoder.Internal.Decoder Methods fmap :: (a0 -> b) -> DecodeArrow o a a0 -> DecodeArrow o a b # (<$) :: a0 -> DecodeArrow o a b -> DecodeArrow o a a0 #
Monad (DecodeArrow o a) Source #	Eliminates all schema information; avoid whenever possible.
Instance details Defined in KDL.Decoder.Internal.Decoder Methods (>>=) :: DecodeArrow o a a0 -> (a0 -> DecodeArrow o a b) -> DecodeArrow o a b # (>>) :: DecodeArrow o a a0 -> DecodeArrow o a b -> DecodeArrow o a b # return :: a0 -> DecodeArrow o a a0 #

liftDecodeM :: (a -> DecodeM b) -> DecodeArrow o a b Source #

withDecoder :: DecodeArrow o a b -> (b -> DecodeM c) -> DecodeArrow o a c Source #

Run actions within a DecodeArrow. Useful for adding post-processing logic.

Example

Expand

decoder = KDL.withDecoder KDL.number $ \x -> do
  when (x > 100)
    KDL.failM $ "argument is too large: " <> (Text.pack . show) x
  pure $ MyVal x

fail :: forall b o. DecodeArrow o Text b Source #

Unconditionally fail the decoder.

Example

Expand

decoder = proc () -> do
  x <- KDL.arg -< ()
  if x > 100
    then KDL.fail -< "argument is too large: " <> (Text.pack . show) x
    else returnA -< ()
  returnA -< x

debug :: Show o => DecodeArrow o a () Source #

Debug the current state of the object being decoded.

Example

Expand

decoder = proc () -> do
  KDL.debug -< ()    -- Node{entries = [Entry{}, Entry{}]}
  x <- KDL.arg -< ()
  KDL.debug -< ()    -- Node{entries = [Entry{}]}
  y <- KDL.arg -< ()
  KDL.debug -< ()    -- Node{entries = []}
  returnA -< (x, y)

DecodeStateM

type DecodeStateM o a = StateT (DecodeState o) DecodeM a Source #

runDecodeStateM :: o -> DecodeHistory o -> DecodeStateM o a -> DecodeM a Source #

DecodeState

class HasDecodeHistory (o :: k) where Source #

Associated Types

data DecodeHistory (o :: k) Source #

Methods

emptyDecodeHistory :: DecodeHistory o Source #

Instances

Instances details

HasDecodeHistory Node Source #

Instance details

Defined in KDL.Decoder.Internal.Decoder

Associated Types

data DecodeHistory Node
Instance details Defined in KDL.Decoder.Internal.Decoder data DecodeHistory Node = DecodeHistory_Node { argsSeen :: Int propsSeen :: Set Identifier childrenHistory :: DecodeHistory NodeList }

Methods

emptyDecodeHistory :: DecodeHistory Node Source #

HasDecodeHistory NodeList Source #

Instance details

Defined in KDL.Decoder.Internal.Decoder

Associated Types

data DecodeHistory NodeList
Instance details Defined in KDL.Decoder.Internal.Decoder data DecodeHistory NodeList = DecodeHistory_NodeList { nodesSeen :: Map Text Int }

Methods

emptyDecodeHistory :: DecodeHistory NodeList Source #

HasDecodeHistory Value Source #

Instance details

Defined in KDL.Decoder.Internal.Decoder

Associated Types

data DecodeHistory Value
Instance details Defined in KDL.Decoder.Internal.Decoder data DecodeHistory Value = DecodeHistory_Value

Methods

emptyDecodeHistory :: DecodeHistory Value Source #

data family DecodeHistory (o :: k) Source #

Instances

Instances details

data DecodeHistory Node Source #
Instance details Defined in KDL.Decoder.Internal.Decoder data DecodeHistory Node = DecodeHistory_Node { argsSeen :: Int propsSeen :: Set Identifier childrenHistory :: DecodeHistory NodeList }
data DecodeHistory NodeList Source #
Instance details Defined in KDL.Decoder.Internal.Decoder data DecodeHistory NodeList = DecodeHistory_NodeList { nodesSeen :: Map Text Int }
data DecodeHistory Value Source #
Instance details Defined in KDL.Decoder.Internal.Decoder data DecodeHistory Value = DecodeHistory_Value

data DecodeState o Source #

The state to track when decoding an object of type o.

At each decode step, some value within o is consumed and the action is recorded in the history.

Constructors

DecodeState
Fields object :: !o history :: DecodeHistory o Not strict, since this only matters for reporting errors