Safe Haskell	None
Language	Haskell2010

Mu.Schema.Registry

Contents

Registry of schemas
Terms without an associated schema

Description

A registry of schemas saves the different schemas supported by an application. Since messages and protocols may evolve, it's useful to keep an updated view of the different shapes of data we can handle.

Examples of registries are found in Kafka and Compendium.

Synopsis

type Registry = Mappings Nat Schema'
fromRegistry :: forall r t. FromRegistry r t => Term -> Maybe t
data Term where
- TRecord :: [Field] -> Term
- TEnum :: Int -> Term
- TSimple :: FieldValue -> Term
data Field where
- Field :: Text -> FieldValue -> Field
data FieldValue where
- FNull :: FieldValue
- FPrimitive :: (Typeable t, Eq t, Ord t, Show t) => t -> FieldValue
- FSchematic :: Term -> FieldValue
- FOption :: Maybe FieldValue -> FieldValue
- FList :: [FieldValue] -> FieldValue
- FMap :: Map FieldValue FieldValue -> FieldValue

Registry of schemas

type Registry = Mappings Nat Schema' Source #

A Registry is defined as a map from version numbers to type-level schemas.

Implementation note: you must write newer schemas at the head of the Registry. Otherwise, older schemas take precedence during conversion.

fromRegistry :: forall r t. FromRegistry r t => Term -> Maybe t Source #

Converts a schemaless term into a value by checking all the possible schemas in a Registry.

Implementation note: schemas are checked in the same order in which they appear in the Registry definition.

Terms without an associated schema

data Term where Source #

Interpretation of a type in a schema.

Constructors

TRecord :: [Field] -> Term	A record given by the value of its fields.
TEnum :: Int -> Term	An enumeration given by one choice.
TSimple :: FieldValue -> Term	A primitive value.

Instances

Eq Term Source #
Instance details Defined in Mu.Schema.Interpretation.Schemaless Methods (==) :: Term -> Term -> Bool # (/=) :: Term -> Term -> Bool #
Ord Term Source #
Instance details Defined in Mu.Schema.Interpretation.Schemaless Methods compare :: Term -> Term -> Ordering # (<) :: Term -> Term -> Bool # (<=) :: Term -> Term -> Bool # (>) :: Term -> Term -> Bool # (>=) :: Term -> Term -> Bool # max :: Term -> Term -> Term # min :: Term -> Term -> Term #
Show Term Source #
Instance details Defined in Mu.Schema.Interpretation.Schemaless Methods showsPrec :: Int -> Term -> ShowS # show :: Term -> String # showList :: [Term] -> ShowS #

data Field where Source #

Interpretation of a field.

Constructors

Field :: Text -> FieldValue -> Field

A single field given by its name and its value.

Instances

Eq Field Source #
Instance details Defined in Mu.Schema.Interpretation.Schemaless Methods (==) :: Field -> Field -> Bool # (/=) :: Field -> Field -> Bool #
Ord Field Source #
Instance details Defined in Mu.Schema.Interpretation.Schemaless Methods compare :: Field -> Field -> Ordering # (<) :: Field -> Field -> Bool # (<=) :: Field -> Field -> Bool # (>) :: Field -> Field -> Bool # (>=) :: Field -> Field -> Bool # max :: Field -> Field -> Field # min :: Field -> Field -> Field #
Show Field Source #
Instance details Defined in Mu.Schema.Interpretation.Schemaless Methods showsPrec :: Int -> Field -> ShowS # show :: Field -> String # showList :: [Field] -> ShowS #

data FieldValue where Source #

Interpretation of a field type, by giving a value of that type.

Constructors

FNull :: FieldValue
FPrimitive :: (Typeable t, Eq t, Ord t, Show t) => t -> FieldValue
FSchematic :: Term -> FieldValue
FOption :: Maybe FieldValue -> FieldValue
FList :: [FieldValue] -> FieldValue
FMap :: Map FieldValue FieldValue -> FieldValue

Instances

Eq FieldValue Source #
Instance details Defined in Mu.Schema.Interpretation.Schemaless Methods (==) :: FieldValue -> FieldValue -> Bool # (/=) :: FieldValue -> FieldValue -> Bool #
Ord FieldValue Source #
Instance details Defined in Mu.Schema.Interpretation.Schemaless Methods compare :: FieldValue -> FieldValue -> Ordering # (<) :: FieldValue -> FieldValue -> Bool # (<=) :: FieldValue -> FieldValue -> Bool # (>) :: FieldValue -> FieldValue -> Bool # (>=) :: FieldValue -> FieldValue -> Bool # max :: FieldValue -> FieldValue -> FieldValue # min :: FieldValue -> FieldValue -> FieldValue #
Show FieldValue Source #
Instance details Defined in Mu.Schema.Interpretation.Schemaless Methods showsPrec :: Int -> FieldValue -> ShowS # show :: FieldValue -> String # showList :: [FieldValue] -> ShowS #