decoding-json

name	decoding-json
description	Decode and parse JSON strings with EYG.

EYG is a strongly typed language. When decoding JSON it MUST also be passed into a useful datastructure. The @json package is for decoding JSON.

Parsing simple values

let {parse: parse, decode: decode} = @json
let result = parse("true", decode.boolean)
// Will return Ok(True({}))
let result = parse("3", decode.integer)
// Will return Ok(3)
let result = parse("\"hi\"", decode.string)
// Will return Ok("hi)

EYG does not support parsing floats

Parsing lists

let {parse: parse, decode: decode} = @json
let decoder = decode.list(decode.integer)
let result = parse("[1, 2, 3]", decoder)
// Will return Ok([1, 2, 3])

Parsing objects

let {parse: parse, decode: decode} = @json
let decoder = decode.object((decoded) -> {
  let foo = decode.field("foo", decode.integer, decoded)
  {foo: foo}
})
parse("{"foo": 3}", decoder),
// will return Ok({foo: 3})

Handling errors

The json library returns string errors.

let {parse: parse, decode: decode} = @json
let result = parse("[]", decode.boolean)
// Will return Error("not a boolean")

The @json package includes the expect function for aborting on error. Use this when making quick scripts

let {parse: parse, decode: decode, expect: expect} = @json
let result = expect(parse("true", decode.boolean), "failed to decode")
// Will return Error("not a boolean")