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 Things 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.