snappy-hs
A pure Haskell implementation of the Snappy compression format.
This library prioritizes portability and simplicity over raw speed. It works reliably across platforms without requiring a C toolchain or dealing with FFI.
Performance
Measured against the native C library (the snappy bindings) on the Google Snappy
test corpus, GHC 9.12 / aarch64, library built with -O2:
| dataset (size) |
decompress vs C |
compress vs C |
| html (100 KB) |
1.8x |
2.3x |
| alice29.txt (149 KB) |
1.5x |
3.1x |
| geo.protodata (116 KB) |
1.8x |
2.4x |
| urls.10K (686 KB) |
2.1x |
2.6x |
| fireworks.jpeg (120 KB, incompressible) |
1.0x |
1.8x |
Decompression runs at roughly C parity (~1-2x) and compression is ~2-3x of C.
The gap that remains is GHC’s native code generator versus a C compiler, not the
algorithm — the encoder mirrors C Snappy’s CompressFragment (skip heuristic,
word-at-a-time match extension, input-sized hash table). Output is validated to be
byte-compatible with the C library in both directions.
Reproduce with cabal bench (criterion, needs the C snappy library installed)
or cabal run snappy-bench (pure, no C dependency).
When to use
- You want cross-platform Snappy encode/decode with a pure Haskell dependency stack
- You’d rather avoid C FFI and the build/packaging complexity that comes with it
When not to use
- You need maximum throughput (use the native library or an FFI-based binding instead).
You would get a lot of mileage from the library too however.
