SagaJson

JSON library top-level: the Json opaque type, the shared Error type, and the decoder-running entry points.

For encoding, see SagaJson.Encode. For decoding primitives and combinators, see SagaJson.Decode.

Types

Json

opaque type Json

A JSON value. Opaque so the internal representation can evolve. Construct with SagaJson.Encode primitives; inspect with SagaJson.Decode combinators.

Error

type Error =
  | InvalidJson String
  | InvalidShape (expected: String) (found: String) (path: List String)
  deriving (Eq, Debug)

Error returned when JSON parsing or decoding fails.

Functions

from_value

fun from_value : Value -> Json

Wrap a Value as a Json. Library-internal; use SagaJson.Encode.

to_value

fun to_value : Json -> Value

Unwrap a Json to its underlying Value. Library-internal; use SagaJson.Decode for ordinary decoding.

parse_string

fun parse_string : String -> Result Json Error

Parse a JSON string into a Json value, without applying a decoder.

run

fun run : (Json -> a needs {Fail Error, ..e}) -> Json -> Result a Error
  needs {..e}

Apply a decoder to an already-parsed Json value, returning a Result.

parse

fun parse : (Json -> a needs {Fail Error, ..e}) -> String -> Result a Error
  needs {..e}

Parse a JSON string and apply a decoder in one step.