#1687: A faster (^)-function. ---------------------------------+--------------------------- Reporter: moonlite@… | Owner: Type: bug | Status: new Priority: normal | Milestone: _|_ Component: Prelude | Version: 6.6.1 Resolution: | Keywords: Operating System: Linux | Architecture: x86 Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: ---------------------------------+--------------------------- Changes (by rwbarton): * cc: rwbarton@… (added) Comment: moonlite's algorithm does squaring and multiplication by the small number `x`, while GHC's algorithm does squaring and multiplication of those squares together in an accumulator. Squaring big integers is a constant factor faster than multiplying different numbers of similar size, so moonlite's algorithm wins on Integer when the numbers involved are large. The downside is that it is not tail-recursive, which costs when multiplications are actually very cheap like for Int. But anyways, how about binding to `mpz_pow_ui` and using a RULE in the case of Integer base? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/1687#comment:13 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler