An effect system is a formal system which describes the computational effects of computer programs, such as side effects. An effect system can be used to provide a compile-time checking of the possible effects of the program.

An effect system is typically an extension of a type system. The term "type and effect system" is sometimes used in this case.

References

C. Hankin, F Nielson, H.R. Nielson. Principles of Program Analysis. ISBN 3540654100

Formal methods | type theory