clojure.walk/macroexpand-all

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Type: function Added: Clojure 1.1 Examples: 4 Runnable: 1

([form])

Recursively performs all possible macroexpansions in form.

Examples

by BertrandDechoux on 2012-06-09 . May have evaluation errors. ▶

(use 'clojure.walk) (macroexpand-all '(-> c (+ 3) (* 2))) (* (+ c 3) 2)

by Sgeo on 2012-12-10 ▶

(use 'clojure.walk) ; tryclj.com and lazybot on #clojure get the following wrong (let [-> inc] (-> 5)) 6 ; Below macroexpansion is supposed to result in equivalent code to the above (macroexpand-all '(let [-> inc] (-> 5))) (let* [-> inc] 5) (let* [-> inc] 5) 5 ; However, as is clear above, it does not

by philos99 on 2014-04-19 . May have evaluation errors. ▶

;; differences between macroexpand-1, macroexpand and macroexpand-all (require '[clojure.pprint :as pp] '[clojure.walk :as walk]) (alter-var-root #'pp/*print-suppress-namespaces* (constantly true)) (defmacro plus [n1 n2] `(+ ~n1 ~n2)) (pp/pprint (macroexpand-1 '(plus 3 4))) ;=> (+ 3 4) (pp/pprint (macroexpand '(plus 3 4))) ;=> (+ 3 4) (defmacro pl [p1 p2] `(plus ~p1 ~p2)) (pp/pprint (macroexpand-1 '(pl 3 4))) ;=> (plus 3 4) (pp/pprint (macroexpand '(pl 3 4))) ;=> (+ 3 4) (defmacro minus [m1 m2] `(- ~m1 ~m2)) (defmacro calc [c1 c2] `(pl ~c1 (minus ~c1 ~c2))) (pp/pprint (macroexpand-1 '(calc 20 30))) ;=> (pl 20 (minus 20 30)) (pp/pprint (macroexpand '(calc 20 30))) ;=> (+ 20 (minus 20 30)) (pp/pprint (walk/macroexpand-all '(calc 20 30))) ;=> (+ 20 (- 20 30))

by owenRiddy on 2023-07-15 . May have evaluation errors. ▶

; macroexpand-all can give different results to what is generated in a real ; evaluation. Here is a code sample that should normally evaluates to `dummy`, ; but `macroexpand-all` generates code that evaluates to `nil`. (defmacro d [] (let [probably-dummy# (-> &env keys first)] `(quote ~probably-dummy#))) (letfn [(dummy [] true)] (d)) ; => dummy (clojure.walk/macroexpand-all '(letfn [(dummy [] true)] (d))) ; => (letfn* [dummy (fn* dummy ([] true))] (quote nil)) (eval (clojure.walk/macroexpand-all '(letfn [(dummy [] true)] (d)))) ; => nil

Note by Sgeo

DO NOT USE THIS FUNCTION, it doesn't handle special forms at all, and, as such, does not in fact expand into the ultimate macroexpansion of the form.

For example,

(require '[clojure.walk :as walk])
(println (walk/macroexpand-all '(quote (let [a 1] a))))

Will print

(quote (let* [a 1] a))

When the correct answer is

(quote (let [a 1] a))

Showing an utter unawareness of proper handling of special forms

DO NOT USE THIS FUNCTION

Note by Cubic

@Sgeo - let is just a macro for let*:

(clojure.repl/source let) =>

(defmacro let
"binding => binding-form init-expr

 Evaluates the exprs in a lexical context in which the symbols in
 the binding-forms are bound to their respective init-exprs or parts
 therein."
 {:added "1.0", :special-form true, :forms '[(let [bindings*] exprs*)]}
 [bindings & body]
 (assert-args let
     (vector? bindings) "a vector for its binding"
     (even? (count bindings)) "an even number of forms in binding vector")
  `(let* ~(destructure bindings) ~@body))

Note by Sgeo

(quote (let [a 1] a)) is '(let [a 1] a) which evaluates to a list containing the symbol let, a vector [a 1], and a symbol a. In this context, the (let [a 1] a) is not code, but mere data, and as such, should not be macroexpanded at all, anymore than a string like "(-> a b c)" should be macroexpanded into "(c (b a))" (and yes, I know that's not the exact macroexpansion).

See also

• clojure.core/macroexpand-1 (0)
• clojure.core/macroexpand (0)

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