(aif 9 (+ 9 %else) (+ 10 %test))
; => (if 9 (+ 9 (+ 10 9)) (+ 10 9))
(aand (+ 30 20) *1)
; => (and (+ 30 20) (+ 30 20))
(aand 1 2 "third" (aand 33 **3))
; => (and 1 2 "third" (and 33 "third"))
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If they're doing multiple evaluations they're a lot less useful than Paul Graham's original anaphoric macros even if they seem superficially more powerful/expressive.
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from the read-me:
"Note that as of right now the symbols are replaced by copying in the expression it references, not by binding to a common variable. Hence not suitable for using with expressions that cause side-effects or involve a lot of computation. That will be changed soon."
I presume, by reading this, these expressions will be evaluated each time they are triggered within the operation, so the answer is - yes they will. But, as the read-me also suggests, this is a "WORK IN PROGRESS" and the author has stated intentions to assign variables, which would solve the issue.
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Certainly these are much more involved than my functions. My aif for example is:
(defmacro aif [expr & body]
`(let [~'it ~expr]
(if ~'it
(do ~(first body))
(do ~@(next body)))))
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(match 123
((and (? even?) it) (~a it " is even"))
(it (~a it " is odd")))
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Interestingly the "%else" would actually be cataphoric, as you refer to what comes next rather than before. So "co-referential macros" would be more fitting if you want to stick with the linguistics analogy. But that'd be too exotic of a term.
And yes as akkartik notes, it causes multiple evaluations right now, mostly just laziness and indecision on my part. I'll probably be giving control over this. Here's a real example of code where you actually want current behavior:
(aif (ns-resolve *ns* 'specs)
(let [c (compile spec :name name)]
(swap! (var-get %test) update (:property c) set/union #{c}))
(do (intern *ns* 'specs (atom {}))
%then))
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You could still have repeated use within a '%then' or '%else' block:
(aif (test)
(something)
(do %then %then))
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Generally the plan is to have a special character control whether it gets bound or inlined, probably `!`. So say `%test!` would get inlined like right now, while using `%test` would bind (and doing both would also be possible). But for a `%then` you'd generally only want to bind if there's 2+ so I could count usages instead.
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