Default nil for optionals

Author: kylebshr

.golden/swiftAdvancedRecordSpec/golden

@@ -2,7 +2,7 @@ public struct Data: CaseIterable, Hashable, Codable {
     public var field0: Int
     public var field1: Int?
 
-    public init(field0: Int, field1: Int?) {
+    public init(field0: Int, field1: Int? = nil) {
         self.field0 = field0
         self.field1 = field1
     }

.golden/swiftBasicDocSpec/golden

@@ -33,7 +33,7 @@ public struct Data {
     /// Second field, it's maybe an Int
     public var second: Int?
 
-    public init(first: Int, second: Int?) {
+    public init(first: Int, second: Int? = nil) {
         self.first = first
         self.second = second
     }

.golden/swiftBasicRecordSpec/golden

@@ -2,7 +2,7 @@ public struct Data {
     public var field0: Int
     public var field1: Int?
 
-    public init(field0: Int, field1: Int?) {
+    public init(field0: Int, field1: Int? = nil) {
         self.field0 = field0
         self.field1 = field1
     }

.golden/swiftRecord0DuplicateRecordFieldSpec/golden

@@ -4,7 +4,7 @@ public struct Data0 {
     /// not a duplicate
     public var field1: Int?
 
-    public init(field0: Int, field1: Int?) {
+    public init(field0: Int, field1: Int? = nil) {
         self.field0 = field0
         self.field1 = field1
     }

.golden/swiftRecord1DuplicateRecordFieldSpec/golden

@@ -4,7 +4,7 @@ public struct Data1 {
     /// not a duplicate
     public var field2: String?
 
-    public init(field0: String, field2: String?) {
+    public init(field0: String, field2: String? = nil) {
         self.field0 = field0
         self.field2 = field2
     }

src/Moat/Pretty/Swift.hs

@@ -305,9 +305,13 @@ prettyStructInitializer indents fields deprecatedFields =
     deprecatedFieldNames = map fst deprecatedFields
     activeFields = filter (\(Field name _ _) -> name `notElem` deprecatedFieldNames) fields
 
+    isOptional :: MoatType -> Bool
+    isOptional (Optional _) = True
+    isOptional _ = False
+
     prettyParam :: Field -> String
     prettyParam (Field fieldName fieldType _) =
-      fieldName ++ ": " ++ prettyMoatType fieldType
+      fieldName ++ ": " ++ prettyMoatType fieldType ++ (if isOptional fieldType then " = nil" else "")
 
     prettyAssignment :: String -> Field -> String
     prettyAssignment indentStr (Field fieldName _ _) =