gleam/json
Types
pub type DecodeError {
UnexpectedEndOfInput
UnexpectedByte(String)
UnexpectedSequence(String)
UnexpectedFormat(List(dynamic.DecodeError))
}
Constructors
-
UnexpectedEndOfInput
-
UnexpectedByte(String)
-
UnexpectedSequence(String)
-
UnexpectedFormat(List(dynamic.DecodeError))
Functions
pub fn array(
from entries: List(a),
of inner_type: fn(a) -> Json,
) -> Json
Encode a list into a JSON array.
Examples
> to_string(array([1, 2, 3], of: int))
"[1, 2, 3]"
pub fn bool(input: Bool) -> Json
Encode a bool into JSON.
Examples
> to_string(bool(False))
"false"
pub fn decode(
from json: String,
using decoder: fn(Dynamic) -> Result(a, List(DecodeError)),
) -> Result(a, gleam/json.DecodeError)
Decode a JSON string into dynamically typed data which can be decoded into
typed data with the gleam/dynamic
module.
Examples
> decode("[1,2,3]", dynamic.list(of: dynamic.int))
Ok([1, 2, 3])
> decode("[", dynamic.list(of: dynamic.int))
Error(UnexpectedEndOfInput)
> decode("1", dynamic.string)
Error(UnexpectedFormat([dynamic.DecodeError("String", "Int", [])]))
pub fn decode_bits(
from json: BitArray,
using decoder: fn(Dynamic) -> Result(a, List(DecodeError)),
) -> Result(a, gleam/json.DecodeError)
Decode a JSON bit string into dynamically typed data which can be decoded
into typed data with the gleam/dynamic
module.
Examples
> decode_bits(<<"[1,2,3]">>, dynamic.list(of: dynamic.int))
Ok([1, 2, 3])
> decode_bits(<<"[">>, dynamic.list(of: dynamic.int))
Error(UnexpectedEndOfInput)
> decode_bits("<<1">>, dynamic.string)
Error(UnexpectedFormat([dynamic.DecodeError("String", "Int", [])]))
pub fn float(input: Float) -> Json
Encode a float into JSON.
Examples
> to_string(float(4.7))
"4.7"
pub fn nullable(
from input: Option(a),
of inner_type: fn(a) -> Json,
) -> Json
Encode an optional value into JSON, using null if it is the None
variant.
Examples
> to_string(nullable(Some(50), of: int))
"50"
> to_string(nullable(None, of: int))
"null"
pub fn object(entries: List(#(String, Json))) -> Json
Encode a list of key-value pairs into a JSON object.
Examples
> to_string(object([
#("game", string("Pac-Man")),
#("score", int(3333360)),
]))
"{\"game\":\"Pac-Mac\",\"score\":3333360}"
pub fn preprocessed_array(from: List(Json)) -> Json
Encode a list of JSON values into a JSON array.
Examples
> to_string(preprocessed_array([int(1), float(2.0), string("3")]))
"[1, 2.0, \"3\"]"
pub fn string(input: String) -> Json
Encode a string into JSON, using normal JSON escaping.
Examples
> to_string(string("Hello!"))
"\"Hello!\""
pub fn to_string(json: Json) -> String
Convert a JSON value into a string.
Where possible prefer the to_string_builder
function as it is faster than
this function, and BEAM VM IO is optimised for sending StringBuilder
data.
Examples
> to_string(array([1, 2, 3], of: int))
"[1,2,3]"
pub fn to_string_builder(json: Json) -> StringBuilder
Convert a JSON value into a string builder.
Where possible prefer this function to the to_string
function as it is
slower than this function, and BEAM VM IO is optimised for sending
StringBuilder
data.
Examples
> to_string_builder(array([1, 2, 3], of: int))
string_builder.from_string("[1,2,3]")