Through the years, there were some attempts to build type systems on top of Erlang. One such attempt happened back in 1997, conducted by Simon Marlow, one of the lead developers of the Glasgow Haskell Compiler, and Philip Wadler, who worked on Haskell's design and has contributed to the theory behind monads (Read the paper on said type system). Joe Armstrong later commented on the paper:
One day Phil phoned me up and announced that a) Erlang needed a type system, b) he had written a small prototype of a type system and c) he had a one year’s sabbatical and was going to write a type system for Erlang and "were we interested?" Answer —"Yes."
Phil Wadler and Simon Marlow worked on a type system for over a year and the results were published in [20]. The results of the project were somewhat disappointing. To start with, only a subset of the language was type-checkable, the major omission being the lack of process types and of type checking inter-process messages.
[^] # Re: A propos d'Erlang
Posté par Bruno Michel (site web personnel) . En réponse au journal Explorer des langages de programmation - édition 2020. Évalué à 4.
Learn you some Erlang a un petit passage sur le sujet :