如何在 REPL 的 Clojure 中显示函数的定义? [英] How can I display the definition of a function in Clojure at the REPL?

问题描述

我正在寻找让 REPL 打印函数的当前定义的能力.有没有办法做到这一点?

I'm looking for the ability to have the REPL print the current definition of a function. Is there any way to do this?

例如，给定:

(defn foo [] (if true "true"))

我想说类似的话

(print-definition foo)

并得到一些类似

(foo [] (if true "true"))

印刷.

推荐答案

source 的替代方案(启动 REPL 时应通过 clojure.repl/source 获得)，从 1.2.0 开始.如果您使用的是 1.1.0 或更低版本，source 在 clojure.contrib 中.repl-utils.)，用于 REPL，而不是查看 .clj 文件中定义的函数:

An alternative to source (which should be available via clojure.repl/source when starting a REPL, as of 1.2.0. If you're working with 1.1.0 or lower, source is in clojure.contrib.repl-utils.), for REPL use, instead of looking at functions defined in a .clj file:

(defmacro defsource
  "Similar to clojure.core/defn, but saves the function's definition in the var's
   :source meta-data."
  {:arglists (:arglists (meta (var defn)))}
  [fn-name & defn-stuff]
  `(do (defn ~fn-name ~@defn-stuff)
       (alter-meta! (var ~fn-name) assoc :source (quote ~&form))
       (var ~fn-name)))

(defsource foo [a b] (+ a b))

(:source (meta #'foo))
;; => (defsource foo [a b] (+ a b))

一个简单的打印定义:

(defn print-definition [v]
  (:source (meta v)))

(print-definition #'foo)

#' 只是一个 reader 宏，从 #' 扩展而来foo 到 (var foo):

#' is just a reader macro, expanding from #'foo to (var foo):

(macroexpand '#'reduce)
;; => (var reduce)

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