A sample CAS client written in Erlang to be used with Yaws web server is available at
Feature-complete Erlang CAS Client for the Cowboy Web Server/Framework: erlang_cas_client_cowboy
Low-level Erlang CAS Client library (used by erlang_cas_client_cowboy): erlang_cas_client_core
A simple CASv1 client example for the Yaws Web Server: index.yaws