Complex sentence: For example, in the GHC library, a general immutable array interface is expressed using a class IArray, where the type class constraint IArray a e expresses the fact that a is an array type capable of holding elements of type e.
Split into simpler sentences: For example, in the GHC standard library, the class IArray expresses a general immutable array interface. In this class, the type class constraint IArray a e means that a is an array type that contains elements of type e.