Programming Language Theory Wiki
PL and PLT
The term “programming language” can be overloaded in many ways. For programmers without much computer science background, they typically think of programming language as designing new languages, mostly at the syntactic level with semantics close to the mainstream languages that they are familiar with. In computer science, programming languages may also refer to compiler design and optimization.
To me, the programming language topics that I am interested in are more about the mathematical theories behind programming languages. This includes lambda calculus, type theory, category theory, etc. Often researchers in this field would call themselves programming language researcher, or PL researcher. But since the field is rather niche and programming languages can mean many things to different people, I prefer to call it with a qualified term programming language theory, or PLT.
Although Wikipedia have an official page about PLT, The term PLT is used informally only by some researchers, such as in the Lisp community. There are research teams and projects that use the acronym PLT, sometimes referring to Programming Language Team, in their name, such as Brown PLT and PLT Scheme (now renamed to Racket). While researchers in other areas, such as ML and dependent types, tend to use the more general term PL.
At MaybeVoid, I use the terms PL and PLT interchangeably to refer to the same thing. When clarification is required, I typically use the long form programming language research, or research topics in programming languages to refer to the same things as PLT. This is just an unofficial convention that I adopt, and may not be officially recognized beyond this website.