#
msgid ""
msgstr ""
msgid "title: Clojure auto curry"
msgstr ""
msgid "layout: post"
msgstr ""
msgid "lang: en"
msgstr ""
msgid "ref: clojure-auto-curry"
msgstr ""
msgid "A naive `add` definition, alongside its usage and macroexpansion:"
msgstr ""
msgid ""
"user=> (defcurry add\n"
" [a b c d e]\n"
" (+ 1 2 3 4 5))\n"
"#'user/add\n"
"\n"
"user=> (add 1)\n"
"#object[clojure.core$partial$fn__5857 0x2c708440 \"clojure.core$partial$fn__5857@2c708440\"]\n"
"\n"
"user=> (add 1 2 3 4)\n"
"#object[clojure.core$partial$fn__5863 0xf4c0e4e \"clojure.core$partial$fn__5863@f4c0e4e\"]\n"
"\n"
"user=> ((add 1) 2 3 4 5)\n"
"15\n"
"\n"
"user=> (((add 1) 2 3) 4 5)\n"
"15\n"
"\n"
"user=> (use 'clojure.pprint)\n"
"nil\n"
"\n"
"user=> (pprint\n"
" (macroexpand\n"
" '(defcurry add\n"
" [a b c d e]\n"
" (+ 1 2 3 4 5))))\n"
"(def\n"
" add\n"
" (clojure.core/fn\n"
" ([a b c d e] (+ 1 2 3 4 5))\n"
" ([a] (clojure.core/partial add a))\n"
" ([a b] (clojure.core/partial add a b))\n"
" ([a b c] (clojure.core/partial add a b c))\n"
" ([a b c d] (clojure.core/partial add a b c d))))\n"
"nil\n"
msgstr ""
msgid ""
"This simplistic `defcurry` definition doesn't support optional parameters, "
"multi-arity, `&` rest arguments, docstrings, etc., but it could certainly "
"evolve to do so."
msgstr ""
msgid ""
"I like how `defcurry` is so short, and abdicates the responsability of doing"
" the multi-arity logic to Clojure's built-in multi-arity support. Simple and"
" elegant."
msgstr ""
msgid "Same Clojure as before, now with auto-currying via macros."
msgstr ""
msgid ""
"Here's a simple macro defined by [Loretta "
"He](http://lorettahe.github.io/clojure/2016/09/22/clojure-auto-curry) to "
"create Clojure functions that are curried on all arguments, relying on "
"Clojure's multi-arity support:"
msgstr ""
msgid "date: 2021-04-24 1"
msgstr ""
msgid ""
"(defmacro defcurry\n"
" [name args & body]\n"
" (let [partials (map (fn [n]\n"
" `(~(subvec args 0 n) (partial ~name ~@(take n args))))\n"
" (range 1 (count args)))]\n"
" `(defn ~name\n"
" (~args ~@body)\n"
" ~@partials)))\n"
msgstr ""
msgid "Comparison with Common Lisp"
msgstr ""
msgid "My attempt at writing an equivalent for Common Lisp gives me:"
msgstr ""
msgid ""
"(defun partial (fn &rest args)\n"
" (lambda (&rest args2)\n"
" (apply fn (append args args2))))\n"
"\n"
"(defun curry-n (n func)\n"
" (cond ((< n 0) (error \"Too many arguments\"))\n"
" ((zerop n) (funcall func))\n"
" (t (lambda (&rest rest)\n"
" (curry-n (- n (length rest))\n"
" (apply #'partial func rest))))))\n"
"\n"
"(defmacro defcurry (name args &body body)\n"
" `(defun ,name (&rest rest)\n"
" (let ((func (lambda ,args ,@body)))\n"
" (curry-n (- ,(length args) (length rest))\n"
" (apply #'partial func rest)))))\n"
msgstr ""
msgid ""
"Without built-in multi-arity support, we have to do more work, like tracking"
" the number of arguments consumed so far. We also have to write `#'partial` "
"ourselves. That is, without dependending on any library, sticking to ANSI "
"Common Lisp."
msgstr ""
msgid "The usage is pretty similar:"
msgstr ""
msgid ""
"* (defcurry add (a b c d e)\n"
" (+ a b c d e))\n"
"ADD\n"
"\n"
"* (add 1)\n"
"#<FUNCTION (LAMBDA (&REST REST) :IN CURRY-N) {100216419B}>\n"
"\n"
"* (funcall (add 1) 2 3 4)\n"
"#<FUNCTION (LAMBDA (&REST REST) :IN CURRY-N) {100216537B}>\n"
"\n"
"* (funcall (add 1) 2 3 4 5)\n"
"15\n"
"\n"
"* (funcall (funcall (add 1) 2 3) 4 5)\n"
"15\n"
"\n"
"* (macroexpand-1\n"
" '(defcurry add (a b c d e)\n"
" (+ a b c d e)))\n"
"(DEFUN ADD (&REST REST)\n"
" (LET ((FUNC (LAMBDA (A B C D E) (+ A B C D E))))\n"
" (CURRY-N (- 5 (LENGTH REST)) (APPLY #'PARTIAL FUNC REST))))\n"
"T\n"
msgstr ""
msgid ""
"This also require `funcall`s, since we return a `lambda` that doesn't live "
"in the function namespace."
msgstr ""
msgid ""
"Like the Clojure one, it doesn't support optional parameters, `&rest` rest "
"arguments, docstrings, etc., but it also could evolve to do so."
msgstr ""
msgid "updated_at: 2021-04-27"
msgstr ""
#~ msgid ""
#~ "(defmacro defcurry\n"
#~ " [fname args & body]\n"
#~ " (let [partials (map (fn [n]\n"
#~ " `(~(subvec args 0 n) (partial ~fname ~@(take n args))))\n"
#~ " (range 1 (count args)))]\n"
#~ " `(defn ~fname\n"
#~ " (~args ~@body)\n"
#~ " ~@partials)))\n"
#~ msgstr ""
#~ msgid "date: 2021-04-24"
#~ msgstr ""
#~ msgid ""
#~ "A simple macro defined by [Loretta "
#~ "He](http://lorettahe.github.io/clojure/2016/09/22/clojure-auto-curry) to "
#~ "create Clojure functions that are curried on all arguments, relying on "
#~ "Clojure's multi-arity support:"
#~ msgstr ""
#~ msgid ""
#~ "Without built-in multi-arity support, we have to do more work, like tracking"
#~ " the number of arguments consumed so far. That is, without dependending on "
#~ "any library, sticking to ANSI Common Lisp."
#~ msgstr ""
#~ msgid ""
#~ "(defun curry-n (n fn)\n"
#~ " (if (= 0 n)\n"
#~ " (funcall fn)\n"
#~ " (lambda (&rest rest)\n"
#~ " (curry-n (something n) fn))))\n"
#~ "\n"
#~ "(defun add (a b c d e)\n"
#~ " (curry-n\n"
#~ " (length '(a b c d e))\n"
#~ " (lambda (&rest rest)\n"
#~ " (apply #'+ rest))))\n"
#~ msgstr ""
#~ msgid ""
#~ "(defun curry-n (n fn)\n"
#~ " (if (= 0 n)\n"
#~ " (funcall fn)\n"
#~ " (lambda (&rest rest)\n"
#~ " (curry-n (something n) fn))))\n"
#~ "\n"
#~ "(defun add (a b c d e)\n"
#~ " (curry-n\n"
#~ " (length '(a b c d e))\n"
#~ " (lambda (&rest rest)\n"
#~ " (apply #'+ rest))))\n"
#~ msgstr ""
