add encoding test

3 files changed, 84 insertions, 2 deletions

diff --git a/src/gleam/json.gleam b/src/gleam/json.gleam
index e1e465b..1c53e3c 100644
--- a/src/gleam/json.gleam
+++ b/src/gleam/json.gleam
@@ -1,8 +1,11 @@
 import gleam/dynamic.{Dynamic}
+import gleam/map
+import gleam/option.{Option}
 import gleam/result
 import gleam/json/types
 
-pub type Json = types.Json
+pub type Json =
+  types.Json
 
 external fn jsone_decode(String) -> types.DecodeResult =
   "jsone_decode" "decode"
@@ -13,3 +16,60 @@ pub fn decode(encoded: String) -> Result(Json, Dynamic) {
     types.Error(types.Badarg(reason)) -> Error(reason)
   }
 }
+
+external fn jsone_encode(Json) -> Result(String, types.DecodeResult) =
+  "jsone_encode" "encode"
+
+pub fn encode(json: Json) -> String {
+  // The encoder only error if input is invalid, i.e. a PID.
+  // This cannot happen when passing in the the Json type.
+  assert Ok(encoded) = jsone_encode(json)
+  encoded
+}
+
+pub fn string(input: String) -> Json {
+  input
+  |> dynamic.from()
+  |> dynamic.unsafe_coerce()
+}
+
+pub fn bool(input: Bool) -> Json {
+  input
+  |> dynamic.from()
+  |> dynamic.unsafe_coerce()
+}
+
+pub fn int(input: Int) -> Json {
+  input
+  |> dynamic.from()
+  |> dynamic.unsafe_coerce()
+}
+
+type Null {
+  Null
+}
+
+pub fn null() -> Json {
+  Null
+  |> dynamic.from()
+  |> dynamic.unsafe_coerce()
+}
+
+pub fn nullable(input: Option(a), mapper: fn(a) -> Json) -> Json {
+  input
+  |> option.map(mapper)
+  |> option.unwrap(null())
+}
+
+pub fn object(entries: List(tuple(String, Json))) -> Json {
+  entries
+  |> map.from_list()
+  |> dynamic.from()
+  |> dynamic.unsafe_coerce()
+}
+
+pub fn list(input: List(Json)) -> Json {
+  input
+  |> dynamic.from()
+  |> dynamic.unsafe_coerce()
+}
diff --git a/src/gleam/json/types.gleam b/src/gleam/json/types.gleam
index 2e6c78f..ad341d0 100644
--- a/src/gleam/json/types.gleam
+++ b/src/gleam/json/types.gleam
@@ -1,6 +1,5 @@
 import gleam/dynamic.{Dynamic}
 
-
 pub external type Json
 
 pub type Failure {
diff --git a/test/gleam/json_test.gleam b/test/gleam/json_test.gleam
index 84f0352..25228bb 100644
--- a/test/gleam/json_test.gleam
+++ b/test/gleam/json_test.gleam
@@ -1,4 +1,5 @@
 import gleam/dynamic
+import gleam/option.{None, Some}
 import gleam/result
 import gleam/json.{Json}
 import gleam/should
@@ -12,3 +13,25 @@ pub fn decode_test() {
   |> result.nil_error()
   |> should.equal(Error(Nil))
 }
+
+pub fn encode_test() {
+  json.string("hello")
+  |> json.encode()
+  |> should.equal("\"hello\"")
+
+  json.null()
+  |> json.encode()
+  |> should.equal("null")
+
+  json.object([tuple("foo", json.int(5))])
+  |> json.encode()
+  |> should.equal("{\"foo\":5}")
+
+  json.nullable(Some(5), json.int)
+  |> json.encode()
+  |> should.equal("5")
+
+  json.nullable(None, json.int)
+  |> json.encode()
+  |> should.equal("null")
+}