singletons contains the basic types and definitions needed to support dependently typed programming techniques in Haskell. This library was originally presented in Dependently Typed Programming with Singletons, published at the Haskell Symposium, 2012. (https://richarde.dev/papers/2012/singletons/paper.pdf) singletons is intended to be a small, foundational library on which other projects can build. As such, singletons has a minimal dependency footprint and supports GHCs dating back to GHC 8.0. For more information, consult the singletons README. You may also be interested in the following related libraries: The singletons-th library defines Template Haskell functionality that allows promotion of term-level functions to type-level equivalents and singling functions to dependently typed equivalents. The singletons-base library uses singletons-th to define promoted and singled functions from the base library, including the Prelude.