posable: A product-of-sums generics library

[ bsd3, generics, library ] [ Propose Tags ]

A generics library that represents a non-recursive Haskell 98 datatype as a product-of-sums. Each type is represented with a single tag, and a product of sums of fields. The tag represents all constructor choices in the type, the fields contain all the values in the type. This representation maps easily to a struct of unions, which is a memory-efficient way to store sum datatypes.

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Change log CHANGELOG.md
Dependencies base (>=4.12.0 && <4.17), finite-typelits (>=0.1.4 && <0.2), generics-sop (>=0.4.0 && <0.6), ghc-typelits-knownnat (>=0.6 && <0.8), template-haskell (>=2.13.0 && <2.19) [details]
License BSD-3-Clause
Author Rick van Hoef
Maintainer Rick van Hoef <hackage@rickvanhoef.nl>
Category Generics
Home page https://github.com/Riscky/posable
Bug tracker https://github.com/Riscky/posable/issues
Source repo head: git clone https://github.com/Riscky/posable
Uploaded by riscky at 2022-06-16T13:46:53Z
Distributions NixOS:
Downloads 33 total (0 in the last 30 days)
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Status Docs available [build log]
Last success reported on 2022-06-16 [all 1 reports]

Readme for posable-

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A library to convert non-recursive Haskell-98 datatypes to a Product-of-Sums representation - and back. This makes it possible to compactly store arrays of (nested) sum types in a struct-of-arrays representation, which is used in array-based languages like Accelerate.


  • The Stack package manager (Tested with stack 2.7.3)
  • stylish-haskell and hlint (for linting only)

Tests and lints

stylish-haskell -r src examples test
hlint src examples test
stack test


stack build
# To build the docs
stack haddock posable


In the examples folder you will find examples that describe how to use this library.