[zsyllepsis]

I don’t think this is accurate. While most popular concatenative languages are stack-based, that is not a requirement for the paradigm. The Wikipedia article calls out a few alternatives, such as Om.

Source: https://en.m.wikipedia.org/wiki/Concatenative_programming_la...

[pxeger1]

APL-family languages are somewhat concatenative but not stack-based. They use grouping rules to form chains of composed functions.