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Joshua Taylor
Joshua Taylor
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Adrian Mouat
Adrian Mouat
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But I keep getting stuck with atts requiring 1 more level of evaluation. E.g. the following needs to evaluate t#:

Why does it seem like one less level of evaluation happens in Clojure?

Definitions of supporting functions:

;note doesn't handle nils because I'm dumb (defn pair [init-lst] (loop [lst init-lst item nil pairs []] (if (empty? lst) pairs (if item (recur (rest lst) nil (conj pairs [item (first lst)])) (recur (rest lst) (first lst) pairs))))) (defn print-tag [name alst closing] (print "<") (when closing (print "\\")) (print name) (doall (map (fn [[h t]] (printf " %s=\"%s\"" h t)) alst)) (print ">"))

(For some reason I didn't do the pair function in the same way as the book which means it doesn't handle nils correctly)

But I keep getting stuck with atts requiring 1 more level evaluation. E.g. the following needs to evaluate t#:

Why does it seem like one less level of evaluation happens in Clojure?

But I keep getting stuck with atts requiring 1 more level of evaluation. E.g. the following needs to evaluate t#:

Why does it seem like one less level of evaluation happens in Clojure?

Definitions of supporting functions:

;note doesn't handle nils because I'm dumb (defn pair [init-lst] (loop [lst init-lst item nil pairs []] (if (empty? lst) pairs (if item (recur (rest lst) nil (conj pairs [item (first lst)])) (recur (rest lst) (first lst) pairs))))) (defn print-tag [name alst closing] (print "<") (when closing (print "\\")) (print name) (doall (map (fn [[h t]] (printf " %s=\"%s\"" h t)) alst)) (print ">"))

(For some reason I didn't do the pair function in the same way as the book which means it doesn't handle nils correctly)

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Adrian Mouat
Adrian Mouat
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Evaluating macro arguments in clojure

I'm trying to translate the following macro from land of lisp into clojure:

(defmacro tag (name atts &body body) `(progn (print-tag ',name (list ,@(mapcar (lambda (x) `(cons ',(car x) ,(cdr x))) (pairs atts))) nil) ,@body (print-tag ',name nil t)))

But I keep getting stuck with atts requiring 1 more level evaluation. E.g. the following needs to evaluate t#:

(defmacro tag [tname atts & body] `(do (print-tag '~tname '[~@(map (fn [[h# t#]] [h# t#]) (pair atts))] nil) ~@body (print-tag '~tname nil true)))

As it produces stuff like:

(tag mytag [color 'blue size 'big]) <mytag color="(quote blue)" size="(quote big)"><\mytag>

Where I want the attribute to evaluated. If I use "(eval t#)" in the above I fall foul of problems like this:

(defn mytag [col] (tag mytag [colour col])) java.lang.UnsupportedOperationException: Can't eval locals (NO_SOURCE_FILE:1)

Any suggestions?

Why does it seem like one less level of evaluation happens in Clojure?