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Rewrote --> to take a placeholder symbol as first argument

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Instead of exporting cantedraw.lib.macro._ and making anyone who wants
to use the --> macro _require_ importing that specific symbol, let's
just make it so the user has to supply a placeholder name before they
do anything.  This means each package provides its own placeholder
symbol which lowers coupling.
This commit is contained in:
Aryadev Chavali
2025-02-14 16:34:15 +00:00
parent 02ff1a3fb3
commit f8a834c0d2
3 changed files with 15 additions and 14 deletions
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20
lib.macros.lisp
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@@ -19,31 +19,31 @@
(in-package :cantedraw.lib.macros)
(defmacro --> (&rest forms)
"Lexically bind current form as `_' for use in the next form, returning the
result of the last form.
(defmacro --> (placeholder &body forms)
"Lexically bind current form as `placeholder' for use in the next form, returning
the result of the last form.
i.e.
(--> (a1 a2...) (b1 b2...) (c1 c2...)) =
(let* ((_ (a1 a2 ...))
(_ (b1 b2 ...))
(_ (c1 c2 ...)))
(let* ((placeholder (a1 a2 ...))
(placeholder (b1 b2 ...))
(placeholder (c1 c2 ...)))
_ )
Also includes transformer where symbols are considered unary functions i.e.
(--> x y) <-> (--> x (y _)).
(--> x y) <-> (--> x (y placeholder)).
"
(if (null forms)
nil
(let ((assignment-forms
(loop :for f :in forms
:for canon-f := (if (symbolp f)
(list f 'cantedraw.lib.macros:_)
(list f placeholder)
f)
:collect `(cantedraw.lib.macros:_ ,canon-f))))
:collect `(,placeholder ,canon-f))))
`(let* ,assignment-forms
cantedraw.lib.macros:_))))
,placeholder))))
(defmacro ->> (&rest forms)
"Make current form the last argument of the next form, returning the last