Why do Clojure devs use "xs" for function args?

Question

In most languages there are conventions around arguments. Such as in nested loops you might use i at the top level, then j, then k.

But in Clojure I don't know what the convention is. I've seen, more often than not, the use of xs in function arguments; so why is that? Does it mean something specific? Are there other conventions?

Answer 1

For the naming convention, you can refer to Clojure library coding standards

Specifically:

Follow clojure.core's example for idiomatic names like pred and coll.

in fns
    f, g, h - function input
    n - integer input usually a size
    index - integer index
    x, y - numbers
    s - string input
    coll - a collection
    pred - a predicate closure
    & more - variadic input
in macros
    expr - an expression
    body - a macro body
    binding - a macro binding vector

Answer 2

I.m not sure it's a standard but very often the convention is x for a simple variable and xs for a variable that represents a sequence. The 's' stands for sequence or a plural, which is convenient.

For instance in destructuring you can use [x & xs] for the first and the following. You will find also idx for index and idxs for more indexes.

Answer 3

Haskell and F# follow the same naming standard/pattern. The xs is the plural formed of x.

See also: https://stackoverflow.com/a/6267767/2370606