ghc-buffer-builder
Library for efficiently building up buffers, one piece at a time
"Data.BufferBuilder" is an efficient library for incrementally building up 'ByteString's, one chunk at a time. Early benchmarks show it is over twice as fast as ByteString Builder, primarily because 'BufferBuilder' is built upon an ST-style restricted monad and mutable state instead of ByteString Builder's monoidal AST. Internally, BufferBuilder is backed by a few C functions. Examination of GHC's output shows nearly optimal code generation with no intermediate thunks -- and thus, continuation passing and its associated indirect jumps and stack traffic only occur when BufferBuilder is asked to append a non-strict ByteString. I benchmarked four approaches with a URL encoding benchmark: * State monad, concatenating ByteStrings: 6.98 us * State monad, ByteString Builder: 2.48 us * Crazy explicit RealWorld baton passing with unboxed state: 28.94 us (GHC generated really awful code for this, but see the revision history for the technique) * C + FFI + ReaderT: 1.11 us Using BufferBuilder is very simple:>import qualified Data.BufferBuilder as BB>>let byteString = BB.runBufferBuilder $ do>BB.appendBS "http">BB.appendChar8 '/'>BB.appendBS "//" This package also provides "Data.BufferBuilder.Utf8" for generating UTF-8 buffers and "Data.BufferBuilder.Json" for encoding data structures into JSON.
BSD-3-Clause