X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=docs%2Fusers_guide%2Fghci.xml;h=9ec07c355e0ab68f1bae0f660e33a9f5ab23ee73;hb=143f4381d242e4a1c3174e8a0732a1e48f00a1aa;hp=26efdee4f74a06f60ff1a11074670284405b4b67;hpb=8eb677bc6758080886aa8b21340cc3470b249b75;p=ghc-hetmet.git

diff --git a/docs/users_guide/ghci.xml b/docs/users_guide/ghci.xml
index 26efdee..9ec07c3 100644
--- a/docs/users_guide/ghci.xml
+++ b/docs/users_guide/ghci.xml
@@ -604,6 +604,12 @@ Prelude IO>
       behaves in the same way for expressions typed at the
       prompt.</para>
 
+      <para>
+        Hint: GHCi will tab-complete names that are in scope; for
+        example, if you run GHCi and type <literal>J&lt;tab&gt;</literal>
+        then GHCi will expand it to <literal>Just </literal>.
+      </para>
+
       <sect3>
 	<title>Qualified names</title>
 
@@ -1072,6 +1078,38 @@ Prelude> :. cmds.ghci
 
       <varlistentry>
 	<term>
+          <literal>:main <replaceable>arg<subscript>1</subscript></replaceable> ... <replaceable>arg<subscript>n</subscript></replaceable></literal>
+          <indexterm><primary><literal>:main</literal></primary></indexterm>
+        </term>
+        <listitem>
+          <para>
+            When a program is compiled and executed, it can use the
+            <literal>getArgs</literal> function to access the
+            command-line arguments.
+            However, we cannot simply pass the arguments to the
+            <literal>main</literal> function while we are testing in ghci,
+            as the <literal>main</literal> function doesn't take its
+            directly.
+          </para>
+
+          <para>
+            Instead, we can use the <literal>:main</literal> command.
+            This runs whatever <literal>main</literal> is in scope, with
+            any arguments being treated the same as command-line arguments,
+            e.g.:
+          </para>
+
+<screen>
+Prelude> let main = System.Environment.getArgs >>= print
+Prelude> :main foo bar
+["foo","bar"]
+</screen>
+
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+	<term>
           <literal>:module <optional>+|-</optional> <optional>*</optional><replaceable>mod<subscript>1</subscript></replaceable> ... <optional>*</optional><replaceable>mod<subscript>n</subscript></replaceable></literal>
           <indexterm><primary><literal>:module</literal></primary></indexterm>
         </term>