feat(stdlib): Json value access utils (#2150)

compiler/test/stdlib/json.test.gr

@@ -35,6 +35,7 @@ from "result" include Result
 from "buffer" include Buffer
 from "char" include Char
 from "list" include List
+from "option" include Option
 use Json.*
 module Validation {
   // Valid
@@ -1099,3 +1100,137 @@ module ToString {
   ) ==
     Ok(Ok(comprehensiveJsonObject))
 }
+
+module Lenses {
+  let num = JsonNumber(123)
+  let str = JsonString("abc")
+  let bool = JsonBoolean(true)
+  let arr = JsonArray([JsonNumber(1), JsonNumber(2), JsonNumber(3)])
+  let obj = JsonObject(
+    [
+      ("num", num),
+      ("string", str),
+      ("bool", bool),
+      ("array", arr),
+      ("null", JsonNull),
+    ],
+  )
+  let nestedObj = JsonObject([("object", JsonObject([("nested", obj)]))])
+  let simpleObj = JsonObject([("property", JsonNumber(10))])
+
+  use Json.Lenses.*
+
+  assert get(json, num) == Some(num)
+  assert set(json, JsonString("hi"), num) == Some(JsonString("hi"))
+  assert map(json, x => JsonArray([x, x]), num) == Some(JsonArray([num, num]))
+
+  assert get(number, num) == Some(123)
+  assert get(string, num) == None
+  assert set(string, "hi", num) == Some(JsonString("hi"))
+  assert map(number, x => x * 2, num) == Some(JsonNumber(246))
+
+  assert get(string, str) == Some("abc")
+  assert get(number, str) == None
+
+  assert get(boolean, bool) == Some(true)
+  assert get(number, bool) == None
+
+  assert get(array, arr) == Some([JsonNumber(1), JsonNumber(2), JsonNumber(3)])
+  assert get(number, arr) == None
+
+  assert get(objectProperties, obj) ==
+    Some(
+      [
+        ("num", num),
+        ("string", str),
+        ("bool", bool),
+        ("array", arr),
+        ("null", JsonNull),
+      ],
+    )
+  assert get(number, obj) == None
+
+  assert get(property("num"), obj) == Some(num)
+  assert get(property("string"), obj) == Some(str)
+  assert get(property("oops"), obj) == None
+  assert get(property("oops"), num) == None
+  assert set(property("bool"), JsonBoolean(false), obj) ==
+    Some(
+      JsonObject(
+        [
+          ("num", num),
+          ("string", str),
+          ("bool", JsonBoolean(false)),
+          ("array", arr),
+          ("null", JsonNull),
+        ],
+      ),
+    )
+  assert set(property("new"), JsonString("newVal"), obj) ==
+    Some(
+      JsonObject(
+        [
+          ("num", num),
+          ("string", str),
+          ("bool", bool),
+          ("array", arr),
+          ("null", JsonNull),
+          ("new", JsonString("newVal")),
+        ],
+      ),
+    )
+  assert map(property("property"), x => JsonArray([x, x]), simpleObj) ==
+    Some(
+      JsonObject([("property", JsonArray([JsonNumber(10), JsonNumber(10)]))]),
+    )
+
+  assert get(property("num") ||> number, obj) == Some(123)
+  assert get(property("null") ||> number, obj) == None
+  assert set(property("object") ||> number, 3, nestedObj) ==
+    Some(JsonObject([("object", JsonNumber(3))]))
+  assert set(property("new") ||> number, 1, JsonObject([])) == None
+  assert map(property("property") ||> number, val => val * 2, simpleObj) ==
+    Some(JsonObject([("property", JsonNumber(20))]))
+  assert map(property("property") ||> string, val => val ++ val, simpleObj) ==
+    None
+
+  assert get(nullable(number), num) == Some(Some(123))
+  assert get(nullable(number), JsonNull) == Some(None)
+  assert get(nullable(number), str) == None
+  assert set(nullable(number), Some(3), str) == Some(JsonNumber(3))
+  assert get(property("num") ||> nullable(number), obj) == Some(Some(123))
+  assert get(property("null") ||> nullable(number), obj) == Some(None)
+  assert set(property("object") ||> nullable(number), Some(3), nestedObj) ==
+    Some(JsonObject([("object", JsonNumber(3))]))
+  assert set(property("object") ||> nullable(number), None, nestedObj) ==
+    Some(JsonObject([("object", JsonNull)]))
+  assert set(property("new") ||> nullable(number), Some(1), JsonObject([])) ==
+    None
+  assert map(
+    property("property") ||> nullable(number),
+    val => Option.map(val => val * 2, val),
+    simpleObj
+  ) ==
+    Some(JsonObject([("property", JsonNumber(20))]))
+  assert map(property("property") ||> nullable(number), val => None, simpleObj) ==
+    Some(JsonObject([("property", JsonNull)]))
+
+  assert get(propertyPath(["object", "nested"]), nestedObj) == Some(obj)
+  assert get(propertyPath(["object", "nested"]), nestedObj) ==
+    get(property("object") ||> property("nested"), nestedObj)
+  assert get(propertyPath(["num"]), obj) == Some(num)
+  assert get(propertyPath([]), obj) == Some(obj)
+  assert get(propertyPath([]), num) == Some(num)
+  assert get(propertyPath(["oops"]), num) == None
+  assert get(propertyPath(["object", "nested", "oops"]), nestedObj) == None
+  assert map(
+    propertyPath(["object", "nested"]) ||> objectProperties,
+    props => List.take(1, props),
+    nestedObj
+  ) ==
+    Some(
+      JsonObject(
+        [("object", JsonObject([("nested", JsonObject([("num", num)]))]))],
+      ),
+    )
+}