Proposal: ~~~~~~~~~ Make `NFData` a fundamental/primitive type-class (by making `deepseq` a GHC-boot package) Discussion deadline: 2 weeks. Note: This is a reboot of a previous unresolved proposal[1] by Johan Tibell with a slightly different emphasis. Current Issues: ~~~~~~~~~~~~~~~ - The `deepseq` package should not depend on `containers` and `array` (ideally `deepseq` would be merged with `base` and `containers`/`array` would define their own `NFData` instances) - Not all data types defined by "core libraries" have `NFData` instances defined (e.g. `time` and `bytestring`). The lack of such "standard" instances causes users of `deepseq` to define local orphan instances - GHC boot packages can't depend on `deepseq` as it is not a GHC-boot package yet, and thus orphan instances are required for those packages -- which would benefit in terms of maintainability[4] and efficiency[3] from being defined locally by having access to the internal representations Rationale: ~~~~~~~~~~ The principal idea this proposal is based upon is that the `NFData` type-class is similarly universal/basic/fundamental as the `Ord`, `Show`, or `Eq` type-classes are -- it might be even desirable to make `NFData` part of a future Haskell Prelude at some point and maybe even allow automatic instance derivation. Building on this idea that `NFData` is a "primitive" type-class, the next best thing that can be done relatively easy and short-term as a transitional step is to 1) make `deepseq` a GHC-boot package[2], 2) remove `deepseq`'s dependancy on `array` and `containers`, 3) move the affected instance definitions to the `array` and `containers` packages respectively, and 4) satisfy the PVP by incrementing package versions where necessary. This should provide a path of least resistance, as no packages depending on `deepseq` would have to be adapted except for maybe PVP-related version constraint widening. Moreover, this would pave the way for a future proposal to merge the `deepseq` into `base` at some later point. References: ~~~~~~~~~~~ [1]: http://hackage.haskell.org/trac/ghc/ticket/4868 [2]: http://www.haskell.org/pipermail/libraries/2010-December/015427.html [3]: http://www.haskell.org/pipermail/libraries/2010-December/015428.html [4]: http://www.haskell.org/pipermail/libraries/2011-January/015488.html -- hvr