Quick and dirty tabwc per Clojure Class assignment

tabwc.clj

;;
;; project.clj
;;

(defproject tabwc "0.0.0-SNAPSHOT"
  :description "A Clojure Class Assignment! CLI util to validate a TAB file, or do a wc."
  :main tabwc.core
  :dependencies [[org.clojure/clojure "1.4.0"]])


;;
;; core.clj
;;

(ns tabwc.core
  (:require [clojure.java.io :as io])
  (:gen-class))

(defn count-words [s]
  (count (re-seq #"\w+" s)))

(defn wc [file]
  (count-words (slurp file)))

(defn tab-count [line]
  (count (re-seq #"\t" line)))

(defn tab-loop [[line & more-lines] header-cnt]
  (if (nil? line)
    "OK"
    (if (= (tab-count line) header-cnt)
      (recur more-lines header-cnt)
      (str "This line is not valid:\n" line " (tab count: " (tab-count line) ")"))))

(defn tab-validate [file]
  (with-open [rdr (io/reader file)]
    (let [lines (line-seq rdr)]
      (if-let [fline (first lines)]
        (let [header-cnt (tab-count fline)]
          (println "Header tab count:" header-cnt)
          (tab-loop (rest lines) header-cnt))
        (println "File appears empty")))))

(def USAGE
 "Usage:
     lein run [FILE] [SWITCH]

   SWTICH should be either of:
     --wc runs a word count on file
     --validate determines whether file is a valid TAB file

   Example usage:
     lein run myfile.txt --validate")

(defn -main [file & [switch]]
  (println
   (condp = switch
     "--wc" (wc file)
     "--validate" (tab-validate file)
     USAGE)))