Given on what has gone on before
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 [A practical subtyping system for Erlang]. 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.
Alpaca’s approach is probably more practical.
