@hackage symbolize1.0.0.1

Symbols, also known as Atoms or Interned Strings, are a common technique to reduce memory usage and improve performance when using many small strings:

A Symbol represents a string (any Textual, so String, Text, ShortText, ByteString, ShortByteString, etc.)

Just like ShortText, ShortByteString and ByteArray, a Symbol has an optimized memory representation, directly wrapping a primitive ByteArray#.

Furthermore, a global symbol table keeps track of which values currently exist, ensuring we always deduplicate symbols. This therefore allows us to: - Check for equality between symbols in constant-time (using pointer equality) - Calculate the hash in constant-time (using StableName) - Keep the memory footprint of repeatedly-seen strings low.

This is very useful if you're frequently comparing strings and the same strings might come up many times. It also makes Symbol a great candidate for a key in e.g. a HashMap or HashSet.

The global symbol table is implemented using weak pointers, which means that unused symbols will be garbage collected. As such, you do not need to be concerned about memory leaks (as is the case with many other symbol table implementations).

The main advantages of Symbolize over other symbol table implementations are:

• Garbage collection: Symbols which are no longer used are automatically cleaned up.

• Support for any Textual type, including String, (strict and lazy) Data.Text, (strict and lazy) Data.ByteString, ShortText, ShortByteString, etc.

• Great memory usage:

• Symbols are simply a (lifted) wrapper around a ByteArray#, which is nicely unpacked by GHC.

• The symbol table is an IntMap that contains weak pointers to these same ByteArray#s and their associated StableName#s

• Great performance:

• unintern is a simple pointer-dereference

• calls to lookup are free of atomic memory barriers (and never have to wait on a concurrent thread running intern)

• Thread-safe

Please see the full README below or on GitHub at https://github.com/Qqwy/haskell-symbolize#readme