lexfiend 2 Mar 2006: A domain-specific language is, generally speaking, a language purpose-built for a specific problem domain. Some examples:
Aside from the concept of domain suitability alluded to above, many have tried to further pin down the defining characteristics of a DSL. For instance, see [L1 ] [L2 ] [L3 ]. Microsoft has its own visual-programming take on DSLs: [L4 ].
So is Tcl a DSL?
Well, no, not in the strict sense of the term. However, Tcl is one of those rare languages in which it's easy to create a proper DSL (i.e. one that minimizes/eliminates everything except the features specific to the domain) while still retaining the full power and expressivity of the base language for the DSL implementation itself. The secret sauce is, of course, safe or [interp create -safe].
[programming by exception - lexfiend: what does it have to do with DSLs?]