interpolate.clj

interpolate.clj

;;; ENVIRONMENTAL IMPACT STATEMENT
;;;
;;; This program was written on recycled memory.
;;; No cons cells were created.
;;;
;;; See also: https://gist.github.com/1676575

(ns interpolate
  (:use [clojure.walk :only (postwalk)])
  (:require [clojure.string :as string]))

(defmacro i
  "This is my string interpolation macro. There are many like it, but
  this one is #{mine}."
  [tmpl]
  {:pre [(string? tmpl)]}
  (let [re #"#\{(.*?)\}"]
    (if-let [matches (re-seq re tmpl)]
      (list* 'format (string/replace tmpl re "%s")
             (map (comp read-string second) matches))
      tmpl)))

(defmacro interpolating
  "Walks body and interpolates all strings."
  [& body]
  `(do ~@(postwalk #(if (string? %) `(i ~%) %) body)))

(comment
  
  (let [x 10]
    (def y 20)
    (println (i "x is #{x}, y is #{y}, and x+y is #{(+ x y)}")))
  
  (interpolating
   (let [x 20]
     (println "hey there, mr. #{x}! how ya doin?")))
  )