Как в одном пункте списка оказались и Тьюринг-полные грамматики, и Forth, Tcl, Lisp? 😊
Я просто процитирую (с сокращениями) ответ на подобные вопросы с Tcler's Wiki:
For years, newcomers to Tcl have asked for its "BNF grammar". comp.lang.tcl then typically hosts a more-or-less unproductive confrontation between Tcl'ers rightly asserting that the questioner doesn't really want a BNF for Tcl, and the "outsider" rightly claiming that, yes, that's exactly what he has in mind.
It's traditional to describe many languages (ALGOL-derived ones, broadly), including C, Java, and Perl with their BNF. Languages such as Forth, Lisp, and Tcl, though, have degenerate syntaxes, designed to give just enough power to implement extensibility. All the functionality in these languages derives from the application of library elements, not syntactic expression. It's moreover typical of the latter that their apparent semantics are mutable at run-time; Lisp, Forth, and Tcl programmers can freely redefine if or while.
Подчёркнутое, наверное, совпадение? ;)