Examples from Essentials Of Programming Langauges in Haskell
RecursiveData.hs covers examples from Chapters 1 and 2. Environment.hs contains the procedural representation of an environment from Chapter 2, used in all the interpreters. LetRec.hs is an implementation of LETREC language, a superset of PROC and LET. ExplicitRefs.hs is an implementation of a language with explicit referencing.