#15842: Exponentiation needs PrelRules -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: (none) Type: feature | Status: new request | Priority: normal | Milestone: 8.8.1 Component: Compiler | Version: 8.6.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Runtime Unknown/Multiple | performance bug Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- When a user writes `a ^ lb`, where `lb` is an integer literal, the type of `lb` defaults to `Integer` unless it's annotated. If `lb` is very small, then `RULES` will expand the whole expression into a few multiplications. If not, the computation will pay the price of `Integer` arithmetic. If we want, we should be able to improve this with a special compilation rule. When `lb :: Integer`, and `0 <= lb <= maxBound :: Word`, we should be able to replace `lb` by the equivalent `Word`. The same problem appears with `^^` and `stimes`. Perhaps those can be fixed up as well, somehow. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15842 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler