From 2df952a2d7051fda168f8abeaeb8ed80a746defe Mon Sep 17 00:00:00 2001
From: RedContritio <591369735@qq.com>
Date: Fri, 30 Aug 2019 21:32:26 +0800
Subject: [PATCH] fixed a bug in 9.rst

RecursiveContents.hs:10:5: error:
      The last statement in a 'do' block must be an expression
      paths <- forM properNames
               $ \ name
                   -> do { let ...;
                           isDirectory <- doesDirectoryExist path;
                           .... }
---
 chp/9.rst | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/chp/9.rst b/chp/9.rst
index c26d361..2ccb40a 100644
--- a/chp/9.rst
+++ b/chp/9.rst
@@ -24,12 +24,13 @@ find命令
     getRecursiveContents topdir = do
       names <- getDirectoryContents topdir
       let properNames = filter (`notElem` [".", ".."]) names
-      paths <- forM properNames $ \name -> do
-        let path = topdir </> name
-        isDirectory <- doesDirectoryExist path
-        if isDirectory
-          then getRecursiveContents path
-          else return [path]
+      paths <- forM properNames 
+          $ \name -> do
+              let path = topdir </> name
+              isDirectory <- doesDirectoryExist path
+              if isDirectory
+                  then getRecursiveContents path
+              else return [path]
       return (concat paths)
 
 单个表达式可以识别像“符合这个全局模式的名称”，“目录项是一个文件”，“当前最后一个被修改的文件”以及其他诸如此类的表达式，通过and或or算子就可以把他们装配起来构成更加复杂的表达式