Version 3.x and 2.7 of the Python language introduces syntax for set comprehensions. It has lambda expressions, closures, list comprehensions, and generators. Introduced in Python 2.4, generator expressions are the lazy evaluation equivalent of list comprehensions. Similar in form to list comprehensions, set comprehensions generate Python sets instead of lists. List comprehensions are the part of a greater family of language constructs called computation expressions. Python 2.7+ also supports set comprehensions and dictionary comprehensions. Racket hash table comprehensions generate Racket hash tables (one implementation of the Racket dictionary type). Filter can also be realized using list comprehensions in languages that support them. Racket set comprehensions generate Racket sets instead of lists. List comprehensions can be expressed with the codice 1 macro's codice 2 keyword. This shows a shorter way of achieving the same result, using MiniD's list comprehensions. List comprehensions are supported in Scheme through the use of the SRFI-42 library. List comprehensions can be expressed with the codice 4 special form.