CODEWITHSUNDEEP
clojurereadfile
G. Swa
G. Swa

Reputation: 47

In Clojure, reading a file which is specified at the command prompt

I am a newbie to Clojure and I am trying to read a file which should be specified at the command line.

When I try the following, giving the file name at REPL, it is working

(ns testpj.core
   (:require [clojure.java.io :as io]))

  (defn readfile [filename]
  (println (System/getProperty "user.dir"))
  (println "Arguments: " filename)
  (slurp filename))

And then I run this at REPL and I get the contents of the file

(require '[testpj.core :as h]) 
  (h/readfile file1.txt)

But when I change the above code to main and I try to give the file name at the command line 

lein run file1.txt



(defn -main [& args]
(println (System/getProperty "user.dir"))
(println "Arguments: " args)
(slurp args))

, I am getting the following error:

"java.lang.IllegalArgumentException: Cannot open <("file1.txt")> as an InputStream."

Can anyone help? Thanks

Upvotes: 3

Views: 1199

Answers (1)

Josh
Josh

Reputation: 4806

The argument vector for -main is [& args], which means that -main accepts any number of arguments. Inside the function, the var args will be bound to a list of the arguments passed to it, or nil if no arguments are given to the function. So, to slurp the first argument passed to a function which takes multiple arguments:

(slurp (first args))

Upvotes: 3

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