Merge pull request #38 from Risto-Stevcev/master

Added some more examples

Author: paf31

test/Main.purs

@@ -2,15 +2,20 @@ module Test.Main where
 
 import Prelude
 
-import Data.Maybe (Maybe(..))
-import Data.Lens (view, traversed, _1, _2, _Just, lens)
-import Data.Lens.Zoom (Traversal, Lens, zoom)
-import Data.Tuple (Tuple(..))
+import Data.Lens (view, traversed, _1, _2, _Just, _Left, lens)
+import Data.Lens.Index (ix)
+import Data.Lens.Fold ((^?))
+import Data.Lens.Zoom (Traversal, TraversalP, Lens, LensP, zoom)
+import Data.Tuple  (Tuple(..))
+import Data.Maybe  (Maybe(..))
+import Data.Either (Either(..))
 
 import Control.Monad.Eff (Eff)
 import Control.Monad.Eff.Console (CONSOLE, logShow)
 import Control.Monad.State (evalState, get)
 
+
+-- Traversing an array nested within a record
 foo :: forall a b r. Lens { foo :: a | r } { foo :: b | r } a b
 foo = lens _.foo (_ { foo = _ })
 
@@ -25,11 +30,31 @@ doc = { foo: Just { bar: [ "Hello", " ", "World" ]} }
 bars :: forall a b. Traversal (Foo a) (Foo b) a b
 bars = foo <<< _Just <<< bar <<< traversed
 
+
+-- Get the index of a deeply nested record
+type BarRec = { foo :: Array (Either { bar :: Array Int } String) }
+data Bar = Bar BarRec
+
+_Bar :: LensP Bar BarRec
+_Bar = lens (\(Bar rec) -> rec) (\_ -> Bar)
+
+doc2 :: Bar
+doc2 = Bar { foo: [Left { bar: [ 1, 2, 3 ] }] }
+
+_0Justbar :: TraversalP Bar (Either { bar :: Array Int } String)
+_0Justbar = _Bar <<< foo <<< ix 0
+
+_1bars :: TraversalP Bar Int
+_1bars = _0Justbar <<< _Left <<< bar <<< ix 1
+
+
+-- Tests state using zoom
 stateTest :: Tuple Int String
 stateTest = evalState go (Tuple 4 ["Foo", "Bar"]) where
   go = Tuple <$> zoom _1 get <*> zoom (_2 <<< traversed) get
 
 main :: forall e. Eff (console :: CONSOLE | e) Unit
 main = do
   logShow $ view bars doc
+  logShow $ doc2 ^? _1bars
   logShow stateTest