Linguistic meaning of 'let' variable in programming [duplicate]

Question

So, I'm a javascript programmer and the new version of JavaScript (ES6) has a new keyword for declaring variables: let, next to the old one var.

I know the difference between these two, but I was asking myself: what does let stand for? var obviously is an abbreviation of "variable", but let? Is it an abbreviation as well? Where does it come from?

I googled this and to my amazement, I couldn't find an answer. I already knew Swift also has a let keyword (they use it for constants), but apparently some other programming languages use it as well.

Unyoke

hmm, I found this: programmers.stackexchange.com/questions/194227/…, but it doesn't really give a clear answer – Unyoke

let stands for... drumroll please... let. You could read let x = 1; as "let x be 1" if that helps. – Zasuwa

it's an english verb; "let this name be this value". – Boltrope

seriously, just that simple? – Unyoke

it stands for lettuce because it leaves itself behind... – Boltrope

@Boltrope - hall of fame comment :-) – Stefansson

"Let" is commonly used in mathematics: en.m.wikipedia.org/wiki/Choice_function – Noisome

Answer 1

It comes from the English word 'let'.

verb: "let", "letting". 1. to allow or permit:

// Hey computer, can you please
let 
// this
night = 'wonderful'

Lisp has the keyword let and it's been around since 1958, though it may have come from even earlier.

Krauss

I've always assumed programming languages inherited it from the language of mathematical proofs, which often say e.g. "Let x be an integer..." – Instructions

@Jordan that's completely likely. You find let used more in functional programming languages which are built on algebraic types and category theory. – Krauss

I always think of it more along the lines of "let the keyword night equal 'wonderful'" but that's probably just me. – Palma

@Jordan I found an example here: en.wikipedia.org/wiki/… – Unyoke