Abstract
Since Erlang is dynamically typed, an Erlang program contains no explicit type information. A static type discipline has some important advantages. It helps the programmer to detect many program errors before running the program, and provides information that can be used in compiler optimizations.

I present a soft-typing system for Erlang. The type system is based on the use of flow analysis (instead of type inference) which makes the system relatively simple and flexible. The system allows recursive types, parameterized types and union types, and will discover any potential type error, but places no restrictions on the set of 'legal' programs.