Jargon REPL and Hackers

By Xah Lee. Date: . Last updated: .

What is REPL? Why's it called REPL? What's the etymology of REPL?

Edict of the Day: any hacker using the term REPL is to be despised upon immediately.

How should one call REPL then?

command-line user interface (CLUI)

Why should one call it CLUI?

Because, first of all, you are a Idiot. That's what that “I” is for. And U don't have a Clue. That's the CLU is for.

It's called CLUI because that's what it is.

REPL is like calling a car “Gas Combust Crank Run”. It's fashionable because you are a Tech Geeker and delights in jargon to hint your in-group status.

Etymology of REPL

There's some bit of linguistic interest here. Note the phrase “read eval print loop”. A unix shell, is REPL, yet nobody calls it that, but “shell”. While, programing language's command line interface, are usually called REPL, since about 2008.

The phrase REPL was popularized by functional language Scheme Lisp, notably by the book Structure and Interpretation of Computer Programs .

The phrase REPL started to become popular around 2008, because many programing languages, started to have a interactive command line interface (For example, Python, Ruby, Clojure ), and it is fashionable to call it REPL because it showcase that the lang has functional programing language feature, which itself is in vogue due to CPU speed running out of juice thus call for parallelism via functional programing. [see Guy Steele Says: Don't Iterate, Recurse, and Get rid of lisp cons!]

The term “shell” itself became popular for this reason. It was associated with “unix” back in 1980s and was the cool kid on the block.

Command Line Interface (REPL) vs Notebook Interface

[see Command Line Interface (REPL) vs Notebook Interface]