gserde

warning: alpha package with poor code hygiene, including assert/panic/todo statements. Use understanding that this package is not ready for primetime.

gleam add gserde

usage

1. Create custom type with a singular variant constructor. See the example src/foo.gleam below.
2. Run gleam run -m gserde.
3. Observe the generated file src/foo_json.gleam.
4. Use the new foo_json module!

// src/foo.gleam
import gleam/option.{type Option}
pub type FooJson {
 Foo(
   a_bool: Bool,
   b_int: Int,
   c_float: Float,
   d_two_tuple: #(Int, String),
   e_option_int: Option(Int),
   f_string_list: List(String),
 )
}

// src/foo_json.gleam
// generated!
import gleam/json
import gleam/dynamic
import internal/foo

pub fn to_json(t: foo.FooJson) {
 json.object([
   #("a_bool", json.bool(t.a_bool)),
   #("b_int", json.int(t.b_int)),
   #("c_float", json.float(t.c_float)),
   #(
     "d_two_tuple",
     json.preprocessed_array([
       json.int(t.d_two_tuple.0),
       json.string(t.d_two_tuple.1),
     ]),
   ),
   #("e_option_int", json.nullable(t.e_option_int, json.int)),
   #("f_string_list", json.array(t.f_string_list, json.string)),
 ])
}

pub fn to_string(t: foo.FooJson) {
 json.to_string(to_json(t))
}

pub fn get_decoder_foo() {
 dynamic.decode6(
   foo.Foo,
   dynamic.field("a_bool", dynamic.bool),
   dynamic.field("b_int", dynamic.int),
   dynamic.field("c_float", dynamic.float),
   dynamic.field("d_two_tuple", dynamic.tuple2(dynamic.int, dynamic.string)),
   dynamic.field("e_option_int", dynamic.optional(dynamic.int)),
   dynamic.field("f_string_list", dynamic.list(dynamic.string)),
 )
}

pub fn from_string(json_str: String) {
 json.decode(json_str, get_decoder_foo())
}

// src/my_module.gleam
import foo
import foo_json

pub fn serialization_identity_test() {
 let foo_1 = foo.Foo(..) // make a Foo

 let foo_2 = foo_1
   |> foo_json.to_string // 👀, stringify the Foo to JSON!
   |> foo_json.from_string // 👀, parse the Foo from JSON!

 foo_1 == foo_2 // pass the identity test
}

You can set DEBUG=1 to get verbose output during codegen.

todo

• complete all cases
• remove all invocations of assert/panic/todo
• support non-gleam primitive types
• handle all module references properly

Further documentation can be found at https://hexdocs.pm/gserde.

Development

gleam test  # Run the tests