I don't think that K and J belong in that category of languages. While they both also welcome a point-free style of programming, an important characteristic of

I don't think that K and J belong in that category of languages. While they both also welcome a point-free style of programming, an important characteristic of concatenative languages is that (almost) any sequence of tokens is a valid sub-program, making it very easy and natural to factor and compose programs from smaller programs. In Forth, if you figure that a sequence of 5 tokens are used often, you don't consider what parameters are used and name them in a function definition. You rip those 5 tokens out verbatim into a word definition, which when called pulls them implicitly off the stack just as if the tokens were in-line.