[SatvikBeri]

This isn't really true – you have languages like Odin that only have a for loop, no while loop, that only supports index-based iteration. Then you have languages like Python that let you loop over an arbitrary iterable, and define your own iterables. Some languages allow conditionals in loops, some don't. Some let you loop over multiple iterables, while some only take one at a time.

Common Lisp happens to be on the upper end of what loop allows – you can use it as a standard for loop pretty easily, but the interface gives you many other options.

[medo-bear]

> Common Lisp happens to be on the upper end of what loop allows – you can use it as a standard for loop pretty easily, but the interface gives you many other options.

If you really wanna get freaky try 'do. It is the heroin addicted cousin of 'loop

https://www.lispworks.com/documentation/HyperSpec/Body/m_do_...

[shawn_w]

`do` is very straightforward and basic compared to the things that `loop` allows.

[medo-bear]

oh no. maybe you have in mind 'dolist or 'dotimes

'do is much more general and way more powerful. in some sense 'loop is the taming of 'do. see for example

https://www.lispworks.com/documentation/lcl50/loop/loop-7.ht...

[shawn_w]

No, I mean do. It's basically just a C style for loop except with a return value. Nothing special.

[medo-bear]

yes the syntax for 'do is simple, like that of lisp. however 'do allows you to make far more complex iteration constructs than 'loop. 'loop is just a DSL to make some of these constructs more concise. read up on it

[lispm]

LOOP has the DO functionality included.

Example:

    CL-USER 18 > (do ((a 1 (+ a 1))
                      (b 10 (* b 1.5))
                      (c nil))

                     ((> a 5) (list a b (reverse c)))

                   (push (* a b) c))

    (6 75.9375 (10 30.0 67.5 135.0 253.125))

    CL-USER 19 > (loop for a = 1 then (+ a 1)
                       and b = 10 then (* b 1.5)
                       and c = NIL then c

                       when (> a 5) do (return (list a b (reverse c)))

                       do (push (* a b) c))

    (6 75.9375 (10 30.0 67.5 135.0 253.125))

[shawn_w]

And then there's Scheme, where there are no iterative loops; all looping is done with recursion. You can build pretty much everything other languages do with loops on top of that, though.

[groovy2shoes]

Not true. Scheme has `do`. See R7RS section 4.2.4 "Iteration".

[shawn_w]

Scheme's `do` is implemented using recursion. There's a sample macro for it in 7.3.