feat: stringifyWithSpace and stringifyWith -> add method similar to elm encode

Author: Serhii Khoma

src/Data/Argonaut/Core.js

@@ -16,6 +16,12 @@ exports.stringify = function (j) {
   return JSON.stringify(j);
 };
 
+exports.stringifyWith = function (i) {
+  return function (j) {
+    return JSON.stringify(j, null, i);
+  }
+};
+
 function isArray(a) {
   return Object.prototype.toString.call(a) === "[object Array]";
 }

src/Data/Argonaut/Core.purs

@@ -37,6 +37,8 @@ module Data.Argonaut.Core
   , jsonEmptyObject
   , jsonSingletonObject
   , stringify
+  , stringifyWith
+  , stringifyWithSpace
   ) where
 
 import Prelude
@@ -45,6 +47,7 @@ import Data.Function.Uncurried (Fn5, runFn5, Fn7, runFn7)
 import Data.Maybe (Maybe(..))
 import Foreign.Object (Object)
 import Foreign.Object as Obj
+import Unsafe.Coerce (unsafeCoerce)
 
 -- | The type of JSON data. The underlying representation is the same as what
 -- | would be returned from JavaScript's `JSON.parse` function; that is,
@@ -178,13 +181,13 @@ toObject = toJsonType caseJsonObject
 
 -- Encoding
 
--- | Construct `Json` from a `Boolean` value 
+-- | Construct `Json` from a `Boolean` value
 foreign import fromBoolean :: Boolean -> Json
 
--- | Construct `Json` from a `Number` value 
+-- | Construct `Json` from a `Number` value
 foreign import fromNumber :: Number -> Json
 
--- | Construct `Json` from a `String` value. If you would like to parse a string 
+-- | Construct `Json` from a `String` value. If you would like to parse a string
 -- | of JSON into valid `Json`, see `jsonParser`.
 foreign import fromString :: String -> Json
 
@@ -235,6 +238,17 @@ jsonSingletonObject key val = fromObject (Obj.singleton key val)
 -- | string value, see `fromString`.
 foreign import stringify :: Json -> String
 
+-- | Converts a `Json` value to a JSON string.
+-- | The first `Int` argument specifies the amount of white space characters to use as indentation.
+-- | This number is capped at 10 (if it is greater, the value is just 10). Values less than 1 indicate that no space should be used.
+stringifyWithSpace :: Int -> Json -> String
+stringifyWithSpace = unsafeCoerce stringifyWith
+
+-- | Converts a `Json` value to a JSON string.
+-- | The first `String` argument is used as indentation.
+-- | If string is longer than 10 characters - only the first 10 characters are used.
+foreign import stringifyWith :: String -> Json -> String
+
 foreign import _caseJson
   :: forall z
    . Fn7