text-1.2.1.3: An efficient packed Unicode text type.

Copyright | (c) Bryan O'Sullivan 2009
License | BSD-style
Maintainer | bos@serpentine.com
Stability | experimental
Portability | GHC
Safe Haskell | None
Language | Haskell98

Data.Text.Internal.Unsafe.Shift

Description

Warning: this is an internal module, and does not have a stable API or name. Functions in this module may not check or enforce preconditions expected by public modules. Use at your own risk!

Fast, unchecked bit shifting functions.

Synopsis

- class UnsafeShift a where
  - shiftL :: a -> Int -> a
  - shiftR :: a -> Int -> a

# Documentation

class UnsafeShift a where

This is a workaround for poor optimisation in GHC 6.8.2. It fails to notice constant-width shifts, and adds a test and branch to every shift. This imposes about a 10% performance hit.

These functions are undefined when the amount being shifted by is greater than the size in bits of a machine Int#.

Methods

shiftL :: a -> Int -> a

shiftR :: a -> Int -> a

Instances

UnsafeShift Int |
UnsafeShift Word16 |
UnsafeShift Word32 |
UnsafeShift Word64 |