Herbie allows plugins to define additional functions, rewrite rules, and even number representations. Plugins are be separately installed. Once installed, Herbie automatically loads and uses them.
The softposit-herbie plugin implements support for posit arithmetic. Install it with:
raco pkg install --auto softposit-herbie
Note that this plugin uses the SoftPosit library, which only supports Linux platforms, and even then is reported to misbehave on some machines.
Once softposit-herbie is installed,
:precision posit16 to inform Herbie that it
should assume the core's inputs and outputs are posit numbers. Other
posit sizes (from 8 to 128 bits) and also quires (for 8, 16, and 32
bits) are available, but are poorly supported.
The plugin functionality is currently highly experimental; if you would like to develop your own plugins, please write to the mailing list.