Data.YAML.Schema

Predefined YAML 1.2 Schema resolvers and encoders as well as support for defining custom resolvers and encoders.

Since: 0.2.0.0

Schema resolvers

YAML 1.2 Schema resolvers

data SchemaResolver

Definition of a YAML 1.2 Schema

A YAML schema defines how implicit tags are resolved to concrete tags and how data is represented textually in YAML.

Constructors

SchemaResolver

Fields

• schemaResolverScalar :: Tag -> ScalarStyle -> Text -> Either String Scalar
• schemaResolverSequence :: Tag -> Either String Tag
• schemaResolverMapping :: Tag -> Either String Tag
• schemaResolverMappingDuplicates :: Bool

failsafeSchemaResolver :: SchemaResolver

"Failsafe" schema resolver as specified in YAML 1.2 / 10.1.2. Tag Resolution

jsonSchemaResolver :: SchemaResolver

Strict JSON schema resolver as specified in YAML 1.2 / 10.2.2. Tag Resolution

coreSchemaResolver :: SchemaResolver

Core schema resolver as specified in YAML 1.2 / 10.3.2. Tag Resolution

Schema encoders

YAML 1.2 Schema encoders

data SchemaEncoder

Since: 0.2.0

Constructors

SchemaEncoder

Fields

• schemaEncoderScalar :: Scalar -> Either String (Tag, ScalarStyle, Text)
• schemaEncoderSequence :: Tag -> Either String Tag
• schemaEncoderMapping :: Tag -> Either String Tag

failsafeSchemaEncoder :: SchemaEncoder

"Failsafe" schema encoder as specified in YAML 1.2 / 10.1.2. Tag Resolution

Since: 0.2.0

jsonSchemaEncoder :: SchemaEncoder

Strict JSON schema encoder as specified in YAML 1.2 / 10.2.2. Tag Resolution

Since: 0.2.0

coreSchemaEncoder :: SchemaEncoder

Core schema encoder as specified in YAML 1.2 / 10.3.2. Tag Resolution

Since: 0.2.0

Custom Schema encoding

According to YAML 1.2 the recommended default SchemaEncoder is coreSchemaEncoder under which Scalars are encoded as follows:

• String which are made of Plain Characters (see isPlainChar), unambiguous (see isAmbiguous) and do not contain any leading/trailing spaces are encoded as Plain Scalar.
• Rest of the strings are encoded in DoubleQuotes
• Booleans are encoded using encodeBool
• Double values are encoded using encodeDouble
• Integral values are encoded using encodeInt

setScalarStyle :: (Scalar -> Either String (Tag, ScalarStyle, Text)) -> SchemaEncoder -> SchemaEncoder

Set the Scalar style in the encoded YAML. This is a function that decides for each Scalar the type of YAML string to output.

WARNING: You must ensure that special strings (like "true"/"false"/"null"/"1234") are not encoded with the Plain style, because then they will be decoded as boolean, null or numeric values. You can use isAmbiguous to detect them.

NOTE: For different SchemaResolvers, different strings are ambiguous. For example, "true" is not ambiguous for failsafeSchemaResolver.

Since: 0.2.0

isPlainChar :: Char -> Bool

These are some characters which can be used in Plain Scalars safely without any quotes (see Indicator Characters).

NOTE: This does not mean that other characters (like "\n" and other special characters like "-?:,[]{}#&*!,>%@`"'") cannot be used in Plain Scalars.

Since: 0.2.0

isAmbiguous :: SchemaResolver -> Text -> Bool

Returns True if the string can be decoded by the given SchemaResolver into a Scalar which is not a of type SStr.

>>> isAmbiguous coreSchemaResolver "true"
True

>>> isAmbiguous failSchemaResolver "true"
False

Since: 0.2.0

encodeDouble :: Double -> Text

Encode Double

Since: 0.2.0

encodeBool :: Bool -> Text

Encode Boolean

Since: 0.2.0

encodeInt :: Integer -> Text

Encode Integer

Since: 0.2.0