mathlib: A Scala package for readable, verifiable and sustainable simulations of formal theory

Formal theory and computational modeling are critical in cognitive science and psychology.Formal systems (e.g., set theory, functions, first-order logic, graph theory) allow scientists to 'conceptually analyze, specify, and formalize intuitions that otherwise remain unexamined' (Guest & Martin, 2021).They make otherwise underspecified theories precise and open for critical reflection (van Rooij & Baggio, 2021).A theory can be formally specified in a computational model using mathematical concepts such as set theory, graph theory, and probability theory.The specification is often followed by analysis to understand precisely what assumptions and consequences the formal theory entails.An important method of analysis is computer simulation, which allows scientists to explore complex model behaviours and derive predictions that otherwise cannot be analytically derived 1 .mathlib is a library for Scala (Odersky, 2008) supporting functional programming that resembles mathematical expressions such as set theory and graph theory.This library was developed to complement the theory development method outlined in the open education book Theoretical modeling for cognitive science and psychology by Blokpoel & van Rooij (2021).To date mathlib is the only library that facilitates implementing computational-level simulations for fully specified formal theories.