cabal-version: 3.0
name:          stock-deepseq
version:       0.1.0.0
x-revision:    1
synopsis:      Derive NFData via the stock plugin
description:
  The <https://hackage.haskell.org/package/stock stock> plugin provides a datatype for deriving and synthesising
  instances at compile time. @stock-deepseq@ extends the <https://hackage.haskell.org/package/stock stock> with
  support for @NFData@ and higher-kinded variants.

  > {-# options_ghc -fplugin Stock -Wno-unused-top-binds #-}
  > 
  > {-# language DerivingVia #-}
  > {-# language DataKinds   #-}
  >
  > import Stock
  > import Stock.NFData
  > import Stock.Override
  > 
  > import Control.Exception
  > 
  > data Person = P { name :: String, age :: Int, secret :: Person }
  >   deriving (Eq, Ord, Show, NFData) via 
  >     Stock Person
  > 
  > -- >> try @SomeException (evaluate (rnf geir))
  > -- Left stack overflow
  > -- >> geir == geir
  > -- <loop>
  > -- >> geir
  > -- P {name = "Geir", age = 10, secret = P {name = "Geir", .. } }
  > geir :: Person
  > geir = P { name = "Geir", age = 10, secret = geir }

  The @rnf@ function triggers the loop, but by pinning @secret@ as an
  ignored field, we can happily force the other fields.

  > newtype Ignore a = Ignore a
  > instance NFData (Ignore a) where rnf _ = ()
  > instance Eq     (Ignore a) where _ == _ = True
  > instance Ord    (Ignore a) where compare _ _ = EQ
  > instance Show   (Ignore a) where show _ = "<ignored>"
  >
  > data Person = P { name :: String, age :: Int, secret :: Person }
  >   deriving (Eq, Ord, Show, NFData) via 
  >     Overriding Person '[ secret via Ignore ]
  >
  > -- >> try @SomeException (evaluate (rnf geir))
  > -- Right ()
  > -- >> geir == geir
  > -- True
  > -- >> geir
  > -- P {name = "Geir", age = 10, secret = <ignored>}

  @stock-deepseq@ provides three instances, that signal to the
  plugin how to derive @NFData@, @NFData1@, @NFData2@.

  > instance DeriveStock  NFData  ..
  > instance DeriveStock1 NFData1 ..
  > instance DeriveStock2 NFData2 ..
license:      BSD-3-Clause
license-file: LICENSE
author:       Baldur Blöndal
maintainer:   baldur.blondal@iohk.io
category:     Type System
build-type:   Simple
tested-with:  GHC == 9.8.1
            , GHC == 9.10.3
            , GHC == 9.12.4
            , GHC == 9.14.1

library
  exposed-modules: Stock.NFData
  build-depends:   base >=4.18 && <5
                 , ghc >=9.8 && <9.16
                 , stock >=0.1 && <0.2
                 , deepseq >=1.4 && <1.6
  hs-source-dirs: .
  default-language: GHC2021
  ghc-options: -Wall

test-suite test
  type:              exitcode-stdio-1.0
  main-is:           Test.hs
  build-depends:     base, stock, stock-deepseq, deepseq
  ghc-options:       -fplugin=Stock
  hs-source-dirs:    test
  default-language:  GHC2021

-- Zero-cost proof: Stock is fully erased
test-suite inspection
  type:              exitcode-stdio-1.0
  main-is:           Inspection.hs
  build-depends:     base, stock, stock-deepseq, deepseq, inspection-testing
  ghc-options:       -fplugin=Stock
  hs-source-dirs:    inspection
  default-language:  GHC2021
  if impl(ghc >= 9.14)
    buildable: False

source-repository head
  type:     git
  location: https://github.com/Icelandjack/stock.git
  subdir:   deepseq