Unwrap nested maybes

src/collector/definitions.js

@@ -141,7 +141,11 @@ function makeType(ctx: Context, node: FlowTypeAnnotation): ?Type {
 function makeMaybe(ctx: Context, node: NullableTypeAnnotation): ?MaybeType {
     const type = makeType(ctx, node.typeAnnotation);
 
-    return type != null ? t.createMaybe(type) : null;
+    if (!type) {
+        return null;
+    }
+
+    return type.kind === 'maybe' ? type : t.createMaybe(type);
 }
 
 function makeComplex(ctx: Context, node: ObjectTypeAnnotation): Type {

src/collector/globals.js

@@ -59,7 +59,7 @@ function stripMaybe(params: (?Type)[], resolve: TypeId => Type): ?Type {
 
     const maybe = resolve(ref.to);
 
-    // TODO: support for unions and nested maybe.
+    // TODO: support for unions.
     if (maybe.kind !== 'maybe') {
         return t.clone(ref);
     }

tests/samples/maybe/source.js

@@ -1,19 +1,15 @@
 type X = {
     x: ?string,
-    xx: ?string[],
+    xx: ?(?string),
-    xxx: (?string)[],
 };
 
 interface Y {
-    y: ?string;
+    y: ?string[];
-    yy: ?string[];
+    yy: ?(?(?string));
-    yyy: (?string)[];
 }
 
 class Z {
-    z: ?string;
+    z: (?string)[];
-    zz: ?string[];
-    zzz: (?string)[];
 }
 
 export {X, Y, Z};

tests/samples/maybe/types.yaml

@@ -8,55 +8,27 @@
     -   name: xx
         value:
             kind: maybe
-            value:
+            value: {kind: string}
-                kind: array
-                items: {kind: string}
-        required: true
-    -   name: xxx
-        value:
-            kind: array
-            items:
-                kind: maybe
-                value: {kind: string}
         required: true
     id: [maybe, X]
 -   kind: record
     fields:
     -   name: y
-        value:
-            kind: maybe
-            value: {kind: string}
-        required: true
-    -   name: yy
         value:
             kind: maybe
             value:
                 kind: array
                 items: {kind: string}
         required: true
-    -   name: yyy
+    -   name: yy
         value:
-            kind: array
+            kind: maybe
-            items:
+            value: {kind: string}
-                kind: maybe
-                value: {kind: string}
         required: true
     id: [maybe, Y]
 -   kind: record
     fields:
     -   name: z
-        value:
-            kind: maybe
-            value: {kind: string}
-        required: true
-    -   name: zz
-        value:
-            kind: maybe
-            value:
-                kind: array
-                items: {kind: string}
-        required: true
-    -   name: zzz
         value:
             kind: array
             items: