[#15] Add lenses for config-related types

Problem: It's quite inconvenient to access config-related records'
fields by hand, especially when it comes to nested ones.

Solution: Add lenses for config-related types and add common lenses
operators & types.

core/nyan-interpolation-core.cabal

@@ -4,7 +4,7 @@ cabal-version: 2.0
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: 454835beb066a76fcd19ff1540bc89d3e2f2732ac9d7164ec5903d0eb782bebd
+-- hash: 53cd08bc1c6de787c00e5dddb89582000ea02db4675760cf87d8f583338306da
 
 name:           nyan-interpolation-core
 version:        0.9
@@ -30,10 +30,13 @@ library
   exposed-modules:
       Text.Interpolation.Nyan.Core
       Text.Interpolation.Nyan.Core.Internal.Base
+      Text.Interpolation.Nyan.Core.Internal.Base.Lens
       Text.Interpolation.Nyan.Core.Internal.Parser
       Text.Interpolation.Nyan.Core.Internal.Processor
       Text.Interpolation.Nyan.Core.Internal.RMode
       Text.Interpolation.Nyan.Core.Internal.Splice
+      Text.Interpolation.Nyan.Lens
+      Text.Interpolation.Nyan.Lens.Type
       Text.Interpolation.Nyan.RModes.Buildable
       Text.Interpolation.Nyan.RModes.CommonExtra
       Text.Interpolation.Nyan.RModes.Show
@@ -91,6 +94,7 @@ test-suite nyan-interpolation-core-tests
   other-modules:
       Test.Customization
       Test.Interpolator
+      Test.Lens
       Test.Parser
       Test.Processor
       Test.Util

core/src/Text/Interpolation/Nyan/Core/Internal/Base/Lens.hs

@@ -0,0 +1,62 @@
+-- SPDX-FileCopyrightText: 2022 Serokell <https://serokell.io/>
+--
+-- SPDX-License-Identifier: MPL-2.0
+
+-- | Exports basic lens for config-related types.
+module Text.Interpolation.Nyan.Core.Internal.Base.Lens where
+
+import Text.Interpolation.Nyan.Core.Internal.Base
+import Text.Interpolation.Nyan.Lens
+
+---------------------------------------------------------------------
+-- Basic lens for 'SwitchesOptions'
+---------------------------------------------------------------------
+
+spacesTrimmingL, indentationStrippingL, leadingNewlineStrippingL,
+  trailingSpacesStrippingL, reducedNewlinesL, monadicL :: Lens' SwitchesOptions Bool
+
+spacesTrimmingL = lens spacesTrimming (\s a -> s { spacesTrimming = a })
+indentationStrippingL = lens indentationStripping (\s a -> s { indentationStripping = a })
+leadingNewlineStrippingL = lens leadingNewlineStripping (\s a -> s { leadingNewlineStripping = a })
+trailingSpacesStrippingL = lens trailingSpacesStripping (\s a -> s { trailingSpacesStripping = a })
+reducedNewlinesL = lens reducedNewlines (\s a -> s { reducedNewlines = a })
+monadicL = lens monadic (\s a -> s { monadic = a })
+
+returnTypeL :: Lens' SwitchesOptions ReturnType
+returnTypeL = lens returnType (\s a -> s { returnType = a })
+
+previewLevelL :: Lens' SwitchesOptions PreviewLevel
+previewLevelL = lens previewLevel (\s a -> s { previewLevel = a })
+
+---------------------------------------------------------------------
+-- Basic lens for 'DefaultSwitchesOptions'
+---------------------------------------------------------------------
+
+defSpacesTrimmingL, defIndentationStrippingL, defLeadingNewlineStrippingL,
+  defTrailingSpacesStrippingL, defReducedNewlinesL, defMonadicL
+    :: Lens' DefaultSwitchesOptions (Maybe Bool)
+
+defSpacesTrimmingL = lens defSpacesTrimming (\s a -> s { defSpacesTrimming = a })
+defIndentationStrippingL = lens defIndentationStripping (\s a -> s { defIndentationStripping = a })
+defLeadingNewlineStrippingL =
+  lens defLeadingNewlineStripping (\s a -> s { defLeadingNewlineStripping = a })
+defTrailingSpacesStrippingL =
+  lens defTrailingSpacesStripping (\s a -> s { defTrailingSpacesStripping = a })
+defReducedNewlinesL = lens defReducedNewlines (\s a -> s { defReducedNewlines = a })
+defMonadicL = lens defMonadic (\s a -> s { defMonadic = a })
+
+defReturnTypeL :: Lens' DefaultSwitchesOptions (Maybe ReturnType)
+defReturnTypeL = lens defReturnType (\s a -> s { defReturnType = a })
+
+---------------------------------------------------------------------
+-- Basic lens for 'InterpolatorOptions'
+---------------------------------------------------------------------
+
+defaultSwitchesOptionsL :: Lens' InterpolatorOptions DefaultSwitchesOptions
+defaultSwitchesOptionsL = lens defaultSwitchesOptions (\s a -> s { defaultSwitchesOptions = a })
+
+valueInterpolatorL :: Lens' InterpolatorOptions ValueInterpolator
+valueInterpolatorL = lens valueInterpolator (\s a -> s { valueInterpolator = a })
+
+invisibleCharsPreviewL :: Lens' InterpolatorOptions InvisibleCharsPreview
+invisibleCharsPreviewL = lens invisibleCharsPreview (\s a -> s { invisibleCharsPreview = a })

core/src/Text/Interpolation/Nyan/Lens.hs

@@ -0,0 +1,33 @@
+-- SPDX-FileCopyrightText: 2022 Serokell <https://serokell.io/>
+--
+-- SPDX-License-Identifier: MPL-2.0
+
+module Text.Interpolation.Nyan.Lens
+  ( module Text.Interpolation.Nyan.Lens.Type
+  , view
+  , over
+  , set
+  , lens
+  , (^.)
+  )
+  where
+
+import Control.Applicative (Const(..))
+import Data.Functor.Identity (Identity(..))
+
+import Text.Interpolation.Nyan.Lens.Type
+
+(^.) :: s -> SimpleGetter s a -> a
+s ^. l = view l s
+
+set :: ASetter' s a -> a -> s -> s
+set l a = runIdentity . l (const $ Identity a)
+
+view :: SimpleGetter s a -> s -> a
+view l = getConst . l Const
+
+over :: ASetter' s a -> (a -> a) -> s -> s
+over l f = runIdentity . l (Identity . f)
+
+lens :: Functor f => (s -> a) -> (s -> a -> s) -> (a -> f a) -> s -> f s
+lens getter setter f s = setter s <$> f (getter s)

core/src/Text/Interpolation/Nyan/Lens/Type.hs

@@ -0,0 +1,17 @@
+-- SPDX-FileCopyrightText: 2022 Serokell <https://serokell.io/>
+--
+-- SPDX-License-Identifier: MPL-2.0
+
+module Text.Interpolation.Nyan.Lens.Type where
+
+import Control.Applicative (Const)
+import Data.Functor.Identity (Identity)
+
+type Lens s t a b = forall f. Functor f => (a -> f b) -> s -> f t
+type Lens' s a = Lens s s a a
+
+type ASetter s t a b = (a -> Identity b) -> s -> Identity t
+type ASetter' s a = ASetter s s a a
+
+type Getting r s a = (a -> Const r a) -> s -> Const r s
+type SimpleGetter s a = forall r. Getting r s a