toy language: n. A language useful for instructional purposes or as a proof-of-concept for some aspect of computer-science theory,

:toy language: n. A language useful for instructional purposes or
as a proof-of-concept for some aspect of computer-science theory,
but inadequate for general-purpose programming. {Bad Thing}s
can result when a toy language is promoted as a general purpose
solution for programming (see {bondage-and-discipline
language}); the classic example is {{Pascal}}. Several moderately
well-known formalisms for conceptual tasks such as programming Turing
machines also qualify as toy languages in a less negative sense.
See also {MFTL}.
-- The AI Hackers Dictionary