#14752: Unboxed sums documentation looks wrong -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: (none) Type: bug | Status: new Priority: high | Milestone: 8.4.2 Component: Documentation | Version: 8.2.2 Keywords: UnboxedSums | Operating System: Unknown/Multiple Architecture: | Type of failure: Documentation Unknown/Multiple | bug Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- According to the documentation,
In the case of enumeration types (like `Bool`), the unboxed sum layout only has an `Int32` field (i.e. the whole thing is represented by an integer).
This does not actually seem to be true. {{{#!hs right :: Bool -> (# (# #) | Bool #) right x = (# | x #) test :: (# (# #) | Bool #) -> Bool test (# (# #) | #) = False test (# | _ #) -> True }}} If the documentation were correct, I would expect `test (right undefined)` to be `undefined`, but it is `True`. Either we should fix the documentation to match reality or the reality to match the documentation. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14752 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler