feat: add assignment operator macros

[scolsen]

These macros apply an operation to the current value of a variable and
then set the variable to the result of the application. They are
effectively sugar for writing (set! <var> (<op> <var> <val>)) and
should be familiar to those who have programmed in imperative languages
like C.

In Carp, all the underlying operations these macros use are interfaces,
so one can flexibly use them for more than just numeric types.

Example usage:

(let-do [dial 0]
  ;; crank it up to 11!
  (while-do (< dial 12)
    (++ dial))
  dial)

;; expanded
(let-do [dial 0]
  ;; crank it up to 11!
  (while-do (< dial 12)
    (set! dial (inc dial)))
  dial)

[hellerve]

The example should read (< dial 12), right? Or am I missing some other context?

[scolsen]

The example should read (< dial 12), right? Or am I missing some other context?

No additional context, you’re correct, that was my mistake. Writing too much go lately haha 🤦‍♂️

[scolsen]

The example should read (< dial 12), right? Or am I missing some other context?

No additional context, you’re correct, that was my mistake. Writing too much go lately haha 🤦‍♂️

Fixed the PR comment, but my mistake will be forever etched in the eternal history of git log 🤷‍♂️

(Also 12 should technically be 11–that’ll teach me to attempt simple arithmetic when distracted)

[eriksvedang]

Nice!