Nearly all programming languages in common use today are strict. Examples include C, C++, Java, Perl (up through version 5), Python, Ruby, Common Lisp, Scheme, and ML. The best known non-strict languages are Haskell, Miranda, and Clean.
In most non-strict languages the non-strictness extends to data constructors. This allows conceptually infinite data structures (such as the list of all prime numbers) to be manipulated in the same way as ordinary finite data structures. It also allows for the use of very large but finite data structures such as the complete game tree of chess.
Non-strictness has several disadvantages which have prevented widespread adoption:
Strict programming languages are often associated with eager evaluation, and non-strict languages with lazy evaluation, but other evaluation strategies are possible in each case. The terms "eager programming language" and "lazy programming language" are often used as synonyms for "strict programming language" and "non-strict programming language" respectively.