= Unpacking primitive fields =

This page describes a proposal to automatically unpack (strict) primitive fields. A primitive fields is a field that when unpacked has a pointer-sized representation. Examples include `Int`, `Word`, `Float`, and `newtype`s thereof.

== Goals and non-goals ==

This proposal is about changing the default behavior of GHC, not changing expressiveness. Users can still use `UNPACK` and `NOUNPACK` to explicitly control the memory representation of fields.

There are two goals:

 1. Reduce the amount of boilerplate experienced programmers have to write: As of Feb 18th 2012, the [http://hackage.haskell.org/package/bytestring bytestring], [http://hackage.haskell.org/package/text text], and [http://hackage.haskell.org/package/containers containers] packages had 46 fields that matched the definition of primitive given above. 43 of these had an explicit `UNPACK` pragma (and the remaining 3 could have had one without changing the performance of the program.)

 2. To provide better defaults for beginner and intermediate level Haskellers. Not unpacking e.g. `Int` fields can have a large, negative effect on performance and many beginner and intermediate level Haskellers are bitten by this.

== Detailed design ==

== Benchmarks ==