Simplify JSON.Decode implementation (rescript-lang#7304)

* Simplify JSON.Decode implementation * CHANGELOG

Author: cknitt

CHANGELOG.md

@@ -38,7 +38,8 @@
 
 - Remove ignore in res_scanner.ml . https://github.com/rescript-lang/rescript/pull/7280
 - Use the new stdlib modules in the analysis tests. https://github.com/rescript-lang/rescript/pull/7295
-- Build with OCaml 5.3.0. https://github.com/rescript-lang/rescript-compiler/pull/7294
+- Build with OCaml 5.3.0. https://github.com/rescript-lang/rescript/pull/7294
+- Simplify JSON.Decode implementation. https://github.com/rescript-lang/rescript/pull/7304
 
 # 12.0.0-alpha.8
 

lib/es6/Stdlib_JSON.js

@@ -69,7 +69,7 @@ function float(json) {
 }
 
 function object(json) {
- if (typeof json === "object" && !Array.isArray(json) && json !== null) {
+ if (typeof json === "object" && json !== null && !Array.isArray(json)) {
  return json;
  }
 

lib/js/Stdlib_JSON.js

@@ -69,7 +69,7 @@ function float(json) {
 }
 
 function object(json) {
- if (typeof json === "object" && !Array.isArray(json) && json !== null) {
+ if (typeof json === "object" && json !== null && !Array.isArray(json)) {
  return json;
  }
 

runtime/Stdlib_JSON.res

@@ -80,22 +80,39 @@ module Encode = {
 }
 
 module Decode = {
- let bool = (json: t) =>
- Stdlib_Type.typeof(json) === #boolean ? Some((Obj.magic(json): bool)) : None
- let null = (json: t) => Obj.magic(json) === Stdlib_Null.null ? Some(Stdlib_Null.null) : None
- let string = (json: t) =>
- Stdlib_Type.typeof(json) === #string ? Some((Obj.magic(json): string)) : None
- let float = (json: t) =>
- Stdlib_Type.typeof(json) === #number ? Some((Obj.magic(json): float)) : None
- let object = (json: t) =>
- if (
- Stdlib_Type.typeof(json) === #object &&
- !Stdlib_Array.isArray(json) &&
- !(Obj.magic(json) === Stdlib_Null.null)
- ) {
- Some((Obj.magic(json): dict<t>))
- } else {
- None
+ let bool = json =>
+ switch json {
+ | Boolean(b) => Some(b)
+ | _ => None
+ }
+
+ let null = json =>
+ switch json {
+ | Null => Some(Stdlib_Null.null)
+ | _ => None
+ }
+
+ let string = json =>
+ switch json {
+ | String(s) => Some(s)
+ | _ => None
+ }
+
+ let float = json =>
+ switch json {
+ | Number(f) => Some(f)
+ | _ => None
+ }
+
+ let object = json =>
+ switch json {
+ | Object(o) => Some(o)
+ | _ => None
+ }
+
+ let array = (json: t) =>
+ switch json {
+ | Array(a) => Some(a)
+ | _ => None
  }
- let array = (json: t) => Stdlib_Array.isArray(json) ? Some((Obj.magic(json): array<t>)) : None
 }