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Diffstat (limited to 'derrida.lisp')
-rw-r--r-- | derrida.lisp | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/derrida.lisp b/derrida.lisp index c9bd495..442c890 100644 --- a/derrida.lisp +++ b/derrida.lisp @@ -86,3 +86,19 @@ And would return else collect `(,term (getf ,plist-var ',term))))) `(let ((,plist-var ,plist)) (symbol-macrolet ,macrolet-bindings ,@body)))) + + +(defun get-nested (plist-tree &rest indicators) + "PLIST-TREE is plist some of whose values are also + PLISTS. INDICATORS are keyes to the plists." + (if (or (null plist-tree) (null indicators)) + plist-tree + (apply #'get-nested (getf plist-tree (car indicators)) (cdr indicators)))) + +(defmacro pluck-nested (keypaths plist &body body) + "Pluck nested binds variables to paths into a plist tree." + (let ((tmp-plist (gensym "plist"))) + `(let ((,tmp-plist ,plist)) + (let ,(loop for (var . path) in keypaths + collect `(,var (get-nested ,tmp-plist ,@path))) + ,@body)))) |