Gerbil Scheme

JSON

To use the bindings from this module:

(import :std/text/json)

read-json

(read-json [input = (current-input-port)]) -> json | error

  input := input source to read JSON data

Returns JSON object from given input source. Signals an error if fails to parse JSON

The input source can be:

  • An input port.
  • A BufferedStringReader.
  • A BufferedReader.

write-json

(write-json obj [sink = (current-output-port)]) -> void | error

  obj  := JSON object
  sink := output sink to write JSON data

Writes JSON object obj optionally given port. Defaults to using current-output-port. Signals an error on failed write.

The output sink can be:

  • An output port.
  • A BufferedStringWriter.
  • A BufferedWriter.
  • A StringWriter.
  • A Writer.

string->json-object

(string->json-object str) -> json | error

  str := a string of JSON data

Parses given str and returns JSON object or signals an error if it fails to parse.

json-object->string

(json-object->string obj) -> string | error

  obj := JSON object

Returns a newly allocated string with JSON object as a string. Signals an error if fails to print JSON.

bytes->json-object

(bytes->json-object str) -> json | error

  bytes := u8vector encoding a UTF-8 string of JSON data

Parses given bytes and returns JSON object or signals an error if it fails to parse.

json-object->bytes

(json-object->bytes obj) -> u8vector | error

  obj := JSON object

Returns a newly allocated u8vector with JSON object as bytes. Signals an error if it fails to print JSON.

port->json-object

(port->json-object port) -> json | error

  port := input port

Parses data on given port and returns JSON object or signals an error if it fails to parse.

json-symbolic-keys

json-symbolic-keys

Boolean parameter to control should decoded hashes have symbols as keys? Defaults to #t. #f means that keys will be strings.

Examples

> (hash->list (string->json-object "{\"a\":1}"))
((a . 1))

> (parameterize ((json-symbolic-keys #f))
    (hash->list (string->json-object "{\"a\":1}")))
(("a" . 1))

json-list-wrapper

json-list-wrapper

Parameter to control how JSON lists should be transformed. Defaults to identity, which means keep them as lists. If bound to list->vector then JSON lists will be parsed as vectors.

Examples

> (string->json-object "[\"a\",1]")
("a" 1)

> (parameterize ((json-list-wrapper list->vector))
    (string->json-object "[\"a\",1]"))
#("a" 1)

trivial-class->json-object

(trivial-class->json-object object) -> json | error

  object := an object

Extracts a printable JSON object from the slots of an object, or signals an error if it fails.

json-object->trivial-class

(json-object->trivial-class class-descriptor json) -> object | error

  class-descriptor := class-descriptor
  json := hash-table

Creates an object of the class corresponding to the class-descriptor by extracting its slots from a json hash-table.

JSON

JSON -> class
JSON::t -> class-descriptor

A class for object that can be printed as JSON. The default :json method is trivial-class->json-object.

pretty-json

(pretty-json object [output])

A function that pretty-prints a JSON object to the specified output as per with-output (defaults to #f, i.e. print to string).

Internally this function uses the external program jq -M . to do the pretty-printing.

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