fix typo in ghci.xml

[ghc-hetmet.git] / docs / users_guide / ghci.xml

diff --git a/docs/users_guide/ghci.xml b/docs/users_guide/ghci.xml
index 4119836..bde1648 100644 (file)
--- a/docs/users_guide/ghci.xml
+++ b/docs/users_guide/ghci.xml
@@ -34,53 +34,9 @@ Prelude>
 </screen>
 
     <para>There may be a short pause while GHCi loads the prelude and
 </screen>
 
     <para>There may be a short pause while GHCi loads the prelude and

-    standard libraries, after which the prompt is shown.  If we follow
-    the instructions and type <literal>:?</literal> for help, we
-    get:</para>
-
-<screen>
- Commands available from the prompt:
-
-   &lt;stmt&gt;                      evaluate/run &lt;stmt&gt;
-   :add &lt;filename&gt; ...         add module(s) to the current target set
-   :browse [*]&lt;module&gt;         display the names defined by &lt;module&gt;
-   :cd &lt;dir&gt;                   change directory to &lt;dir&gt;
-   :def &lt;cmd&gt; &lt;expr&gt;           define a command :&lt;cmd&gt;
-   :edit &lt;file&gt;                edit file
-   :edit                       edit last module
-   :help, :?                   display this list of commands
-   :info [&lt;name&gt; ...]          display information about the given names
-   :load &lt;filename&gt; ...        load module(s) and their dependents
-   :module [+/-] [*]&lt;mod&gt; ...  set the context for expression evaluation
-   :main [&lt;arguments&gt; ...]     run the main function with the given arguments
-   :reload                     reload the current module set
-
-   :set &lt;option&gt; ...           set options
-   :set args &lt;arg&gt; ...         set the arguments returned by System.getArgs
-   :set prog &lt;progname&gt;        set the value returned by System.getProgName
-   :set prompt &lt;prompt&gt;        set the prompt used in GHCi
-   :set editor &lt;cmd&gt;        set the command used for :edit
-
-   :show modules               show the currently loaded modules
-   :show bindings              show the current bindings made at the prompt
-
-   :ctags [&lt;file&gt;]             create tags file for Vi (default: "tags")
-   :etags [&lt;file&gt;]             create tags file for Emacs (default: "TAGS")
-   :type &lt;expr&gt;                show the type of &lt;expr&gt;
-   :kind &lt;type&gt;                show the kind of &lt;type&gt;
-   :undef &lt;cmd&gt;                undefine user-defined command :&lt;cmd&gt;
-   :unset &lt;option&gt; ...         unset options
-   :quit                       exit GHCi
-   :!&lt;command&gt;                 run the shell command &lt;command&gt;
-
- Options for ':set' and ':unset':
-
-    +r            revert top-level expressions after each evaluation
-    +s            print timing/memory stats after each evaluation
-    +t            print type after evaluation
-    -&lt;flags&gt;      most GHC command line flags can also be set here
-                         (eg. -v2, -fglasgow-exts, etc.)
-</screen>
+    standard libraries, after which the prompt is shown. As the banner
+    says, you can type <literal>:?</literal> to see the list of commands
+    available, and a half line description of each of them.</para>

 
     <para>We'll explain most of these commands as we go along.  For
     Hugs users: many things work the same as in Hugs, so you should be
 
     <para>We'll explain most of these commands as we go along.  For
     Hugs users: many things work the same as in Hugs, so you should be

@@ -263,19 +219,17 @@ Ok, modules loaded: Main.
 <screen>
 Prelude> :! ghc -c D.hs
 Prelude> :load A
 <screen>
 Prelude> :! ghc -c D.hs
 Prelude> :load A

-Skipping  D                ( D.hs, D.o )
-Compiling C                ( C.hs, interpreted )

 Compiling B                ( B.hs, interpreted )
 Compiling B                ( B.hs, interpreted )

+Compiling C                ( C.hs, interpreted )

 Compiling A                ( A.hs, interpreted )
 Ok, modules loaded: A, B, C, D.
 *Main>
 </screen>
 
 Compiling A                ( A.hs, interpreted )
 Ok, modules loaded: A, B, C, D.
 *Main>
 </screen>
 

-    <para>In the messages from the compiler, we see that it skipped D,
-    and used the object file <filename>D.o</filename>.  The message
-    <literal>Skipping</literal> <replaceable>module</replaceable>
-    indicates that compilation for <replaceable>module</replaceable>
-    isn't necessary, because the source and everything it depends on
+    <para>In the messages from the compiler, we see that there is no line
+    for <literal>D</literal>. This is because
+    it isn't necessary to compile <literal>D</literal>,
+    because the source and everything it depends on

     is unchanged since the last compilation.</para>
 
     <para>At any time you can use the command 
     is unchanged since the last compilation.</para>
 
     <para>At any time you can use the command 

@@ -291,7 +245,7 @@ B                ( B.hs, interpreted )
 A                ( A.hs, interpreted )
 *Main></screen>
 
 A                ( A.hs, interpreted )
 *Main></screen>
 

-    <para>If we now modify the source of D (or pretend to: using Unix
+    <para>If we now modify the source of D (or pretend to: using the Unix

     command <literal>touch</literal> on the source file is handy for
     this), the compiler will no longer be able to use the object file,
     because it might be out of date:</para>
     command <literal>touch</literal> on the source file is handy for
     this), the compiler will no longer be able to use the object file,
     because it might be out of date:</para>

@@ -300,9 +254,6 @@ A                ( A.hs, interpreted )
 *Main> :! touch D.hs
 *Main> :reload
 Compiling D                ( D.hs, interpreted )
 *Main> :! touch D.hs
 *Main> :reload
 Compiling D                ( D.hs, interpreted )

-Skipping  C                ( C.hs, interpreted )
-Skipping  B                ( B.hs, interpreted )
-Skipping  A                ( A.hs, interpreted )

 Ok, modules loaded: A, B, C, D.
 *Main> 
 </screen>
 Ok, modules loaded: A, B, C, D.
 *Main> 
 </screen>

@@ -318,8 +269,8 @@ Ok, modules loaded: A, B, C, D.
 *Main> :! ghc -c C.hs
 *Main> :load A
 Compiling D                ( D.hs, interpreted )
 *Main> :! ghc -c C.hs
 *Main> :load A
 Compiling D                ( D.hs, interpreted )

-Compiling C                ( C.hs, interpreted )

 Compiling B                ( B.hs, interpreted )
 Compiling B                ( B.hs, interpreted )

+Compiling C                ( C.hs, interpreted )

 Compiling A                ( A.hs, interpreted )
 Ok, modules loaded: A, B, C, D.
 </screen>
 Compiling A                ( A.hs, interpreted )
 Ok, modules loaded: A, B, C, D.
 </screen>

@@ -342,8 +293,6 @@ Ok, modules loaded: A, B, C, D.
 
 <screen>
 *Main> :load A
 
 <screen>
 *Main> :load A

-Skipping  D                ( D.hs, D.o )
-Skipping  C                ( C.hs, C.o )

 Compiling B                ( B.hs, interpreted )
 Compiling A                ( A.hs, interpreted )
 Ok, modules loaded: A, B, C, D.
 Compiling B                ( B.hs, interpreted )
 Compiling A                ( A.hs, interpreted )
 Ok, modules loaded: A, B, C, D.

@@ -354,7 +303,7 @@ Ok, modules loaded: A, B, C, D.
     when working on a large program is to occasionally run
     <literal>ghc &ndash;&ndash;make</literal> to compile the whole project (say
     before you go for lunch :-), then continue working in the
     when working on a large program is to occasionally run
     <literal>ghc &ndash;&ndash;make</literal> to compile the whole project (say
     before you go for lunch :-), then continue working in the

-    interpreter.  As you modify code, the new modules will be
+    interpreter.  As you modify code, the changed modules will be

     interpreted, but the rest of the project will remain
     compiled.</para>
 
     interpreted, but the rest of the project will remain
     compiled.</para>
 

@@ -615,7 +564,7 @@ Prelude IO>
       <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>
       <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>.
+        then GHCi will expand it to &ldquo;<literal>Just </literal>&rdquo;.

       </para>
 
       <sect3>
       </para>
 
       <sect3>

@@ -766,7 +715,7 @@ it &lt;- <replaceable>e</replaceable>
         </listitem>
     </orderedlist>
     At the GHCi prompt, or with GHC if the
         </listitem>
     </orderedlist>
     At the GHCi prompt, or with GHC if the

-    <literal>-fextended-default-rules</literal> flag is given,
+    <literal>-XExtendedDefaultRules</literal> flag is given,

     the following additional differences apply:
     <itemizedlist>
         <listitem>
     the following additional differences apply:
     <itemizedlist>
         <listitem>

@@ -815,8 +764,8 @@ def = toEnum 0
     instance that returns <literal>IO a</literal>.
     However, it is only able to return
     <literal>undefined</literal>
     instance that returns <literal>IO a</literal>.
     However, it is only able to return
     <literal>undefined</literal>

-    (the reason for the instance having this type is to not require
-    extensions to the class system), so if the type defaults to
+    (the reason for the instance having this type is so that printf
+    doesn't require extensions to the class system), so if the type defaults to

     <literal>Integer</literal> then ghci gives an error when running a
     printf.
    </para>
     <literal>Integer</literal> then ghci gives an error when running a
     printf.
    </para>

@@ -839,7 +788,7 @@ def = toEnum 0
     <para>The debugger provides the following:
     <itemizedlist>
         <listitem>
     <para>The debugger provides the following:
     <itemizedlist>
         <listitem>

-          <para>The abilty to set a <firstterm>breakpoint</firstterm> on a
+          <para>The ability to set a <firstterm>breakpoint</firstterm> on a

             function definition or expression in the program.  When the function
             is called, or the expression evaluated, GHCi suspends 
             execution and returns to the prompt, where you can inspect the
             function definition or expression in the program.  When the function
             is called, or the expression evaluated, GHCi suspends 
             execution and returns to the prompt, where you can inspect the

@@ -1068,7 +1017,7 @@ right :: [a]
       <para>The execution continued at the point it previously stopped, and has
         now stopped at the breakpoint for a second time.</para>
 
       <para>The execution continued at the point it previously stopped, and has
         now stopped at the breakpoint for a second time.</para>
 

-      <sect3 id="setting-breakpoings">
+      <sect3 id="setting-breakpoints">

         <title>Setting breakpoints</title>
 
         <para>Breakpoints can be set in various ways.  Perhaps the easiest way to
         <title>Setting breakpoints</title>
 
         <para>Breakpoints can be set in various ways.  Perhaps the easiest way to

@@ -1131,7 +1080,7 @@ right :: [a]
         <title>Listing and deleting breakpoints</title>
 
         <para>The list of breakpoints currently enabled can be displayed using
         <title>Listing and deleting breakpoints</title>
 
         <para>The list of breakpoints currently enabled can be displayed using

-          <literal>:show&nbsp;breaks</literal></para>:
+          <literal>:show&nbsp;breaks</literal>:</para>

 <screen>
 *Main> :show breaks
 [0] Main qsort.hs:1:11-12
 <screen>
 *Main> :show breaks
 [0] Main qsort.hs:1:11-12

@@ -1539,7 +1488,7 @@ Just 20
         </listitem>
        <listitem><para>
          Implicit parameters (see <xref linkend="implicit-parameters"/>) are only available 
         </listitem>
        <listitem><para>
          Implicit parameters (see <xref linkend="implicit-parameters"/>) are only available 

-         at the scope of a breakpoint if there is a explicit type signature.
+         at the scope of a breakpoint if there is an explicit type signature.

        </para>
         </listitem>
       </itemizedlist>
        </para>
         </listitem>
       </itemizedlist>

@@ -1567,9 +1516,7 @@ $ ghci Main.hs
 
     <para>Most of the command-line options accepted by GHC (see <xref
     linkend="using-ghc"/>) also make sense in interactive mode.  The ones
 
     <para>Most of the command-line options accepted by GHC (see <xref
     linkend="using-ghc"/>) also make sense in interactive mode.  The ones

-    that don't make sense are mostly obvious; for example, GHCi
-    doesn't generate interface files, so options related to interface
-    file generation won't have any effect.</para>
+    that don't make sense are mostly obvious.</para>

 
     <sect2>
       <title>Packages</title>
 
     <sect2>
       <title>Packages</title>

@@ -1585,12 +1532,7 @@ $ ghci Main.hs
 
 <screen>
 $ ghci -package readline
 
 <screen>
 $ ghci -package readline

-   ___         ___ _
-  / _ \ /\  /\/ __(_)
- / /_\// /_/ / /  | |      GHC Interactive, version 6.6, for Haskell 98.
-/ /_\\/ __  / /___| |      http://www.haskell.org/ghc/
-\____/\/ /_/\____/|_|      Type :? for help.
-
+GHCi, version 6.8.1: http://www.haskell.org/ghc/  :? for help

 Loading package base ... linking ... done.
 Loading package readline-1.0 ... linking ... done.
 Prelude> 
 Loading package base ... linking ... done.
 Loading package readline-1.0 ... linking ... done.
 Prelude> 

@@ -1762,16 +1704,6 @@ $ ghci -lm
 
       <varlistentry>
        <term>
 
       <varlistentry>
        <term>

-          <literal>:continue</literal> 
-          <indexterm><primary><literal>:continue</literal></primary></indexterm>
-        </term>
-       <listitem><para>Continue the current evaluation, when stopped at a
-            breakpoint.</para>
-       </listitem>
-      </varlistentry>
-
-      <varlistentry>
-       <term>

           <literal>:cmd</literal> <replaceable>expr</replaceable>
           <indexterm><primary><literal>:cmd</literal></primary></indexterm>
         </term>
           <literal>:cmd</literal> <replaceable>expr</replaceable>
           <indexterm><primary><literal>:cmd</literal></primary></indexterm>
         </term>

@@ -1786,6 +1718,16 @@ $ ghci -lm
 
       <varlistentry>
        <term>
 
       <varlistentry>
        <term>

+          <literal>:continue</literal> 
+          <indexterm><primary><literal>:continue</literal></primary></indexterm>
+        </term>
+       <listitem><para>Continue the current evaluation, when stopped at a
+            breakpoint.</para>
+       </listitem>
+      </varlistentry>
+
+      <varlistentry>
+       <term>

          <literal>:ctags</literal> <optional><replaceable>filename</replaceable></optional>
          <literal>:etags</literal> <optional><replaceable>filename</replaceable></optional>
          <indexterm><primary><literal>:etags</literal></primary>
          <literal>:ctags</literal> <optional><replaceable>filename</replaceable></optional>
          <literal>:etags</literal> <optional><replaceable>filename</replaceable></optional>
          <indexterm><primary><literal>:etags</literal></primary>

@@ -1795,7 +1737,8 @@ $ ghci -lm
        </term>
        <listitem>
          <para>Generates a &ldquo;tags&rdquo; file for Vi-style editors
        </term>
        <listitem>
          <para>Generates a &ldquo;tags&rdquo; file for Vi-style editors

-           (<literal>:ctags</literal>) or Emacs-style editors (<literal>etags</literal>).  If
+           (<literal>:ctags</literal>) or
+        Emacs-style editors (<literal>:etags</literal>).  If

            no filename is specified, the defaulit <filename>tags</filename> or
            <filename>TAGS</filename> is
            used, respectively.  Tags for all the functions, constructors and
            no filename is specified, the defaulit <filename>tags</filename> or
            <filename>TAGS</filename> is
            used, respectively.  Tags for all the functions, constructors and

@@ -1903,6 +1846,15 @@ Prelude> :. cmds.ghci
 
       <varlistentry>
        <term>
 
       <varlistentry>
        <term>

+          <literal>:etags</literal> 
+        </term>
+       <listitem>
+         <para>See <literal>:ctags</literal>.</para>
+       </listitem>
+      </varlistentry>
+
+      <varlistentry>
+       <term>

           <literal>:force <replaceable>identifier</replaceable> ...</literal>
           <indexterm><primary><literal>:force</literal></primary></indexterm>
         </term>
           <literal>:force <replaceable>identifier</replaceable> ...</literal>
           <indexterm><primary><literal>:force</literal></primary></indexterm>
         </term>

@@ -1971,6 +1923,12 @@ Prelude> :. cmds.ghci
          will be printed.  If <replaceable>name</replaceable> has
          been loaded from a source file, then GHCi will also display
          the location of its definition in the source.</para>
          will be printed.  If <replaceable>name</replaceable> has
          been loaded from a source file, then GHCi will also display
          the location of its definition in the source.</para>

+         <para>For types and classes, GHCi also summarises instances that
+         mention them.  To avoid showing irrelevant information, an instance
+         is shown only if (a) its head mentions <replaceable>name</replaceable>, 
+         and (b) all the other things mentioned in the instance
+         are in scope (either qualified or otherwise) as a result of 
+         a <literal>:load</literal> or <literal>:module</literal> commands. </para>

        </listitem>
       </varlistentry>
 
        </listitem>
       </varlistentry>
 

@@ -2039,7 +1997,7 @@ Prelude> :. cmds.ghci
             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
             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.
+            arguments directly.

           </para>
 
           <para>
           </para>
 
           <para>

@@ -2084,7 +2042,7 @@ Prelude> :main foo bar
        <listitem>
          <para>Prints a value without forcing its evaluation.
             <literal>:print</literal> may be used on values whose types are
        <listitem>
          <para>Prints a value without forcing its evaluation.
             <literal>:print</literal> may be used on values whose types are

-            unkonwn or partially known, which might be the case for local
+            unknown or partially known, which might be the case for local

             variables with polymorphic types at a breakpoint.  While inspecting
             the runtime value, <literal>:print</literal> attempts to
             reconstruct the type of the value, and will elaborate the type in
             variables with polymorphic types at a breakpoint.  While inspecting
             the runtime value, <literal>:print</literal> attempts to
             reconstruct the type of the value, and will elaborate the type in

@@ -2104,7 +2062,7 @@ Prelude> :main foo bar
           <indexterm><primary><literal>:quit</literal></primary></indexterm>
         </term>
        <listitem>
           <indexterm><primary><literal>:quit</literal></primary></indexterm>
         </term>
        <listitem>

-         <para>Quits GHCi.  You can also quit by typing a control-D
+         <para>Quits GHCi.  You can also quit by typing control-D

          at the prompt.</para>
        </listitem>
       </varlistentry>
          at the prompt.</para>
        </listitem>
       </varlistentry>

@@ -2249,7 +2207,7 @@ Prelude> :main foo bar
           <indexterm><primary><literal>:show modules</literal></primary></indexterm>
         </term>
        <listitem>
           <indexterm><primary><literal>:show modules</literal></primary></indexterm>
         </term>
        <listitem>

-         <para>Show the list of modules currently load.</para>
+         <para>Show the list of modules currently loaded.</para>

        </listitem>
       </varlistentry>
 
        </listitem>
       </varlistentry>
 

@@ -2360,7 +2318,7 @@ Prelude> :main foo bar
 
     <para>The <literal>:set</literal> command sets two types of
     options: GHCi options, which begin with
 
     <para>The <literal>:set</literal> command sets two types of
     options: GHCi options, which begin with

-    &lsquo;<literal>+</literal>&rdquo; and &ldquo;command-line&rdquo;
+    &lsquo;<literal>+</literal>&rsquo;, and &ldquo;command-line&rdquo;

     options, which begin with &lsquo;-&rsquo;.  </para>
 
     <para>NOTE: at the moment, the <literal>:set</literal> command
     options, which begin with &lsquo;-&rsquo;.  </para>
 
     <para>NOTE: at the moment, the <literal>:set</literal> command

@@ -2472,9 +2430,10 @@ Prelude> :set -fno-glasgow-exts
     <indexterm><primary>startup</primary><secondary>files, GHCi</secondary>
     </indexterm>
 
     <indexterm><primary>startup</primary><secondary>files, GHCi</secondary>
     </indexterm>
 

-    <para>When it starts, GHCi always reads and executes commands from
-    <filename>$HOME/.ghci</filename>, followed by
-    <filename>./.ghci</filename>.</para>
+    <para>When it starts, unless the <literal>-ignore-dot-ghci</literal>
+    flag is given, GHCi reads and executes commands from
+    <filename>./.ghci</filename>, followed by
+    <filename>$HOME/.ghci</filename>.</para>

 
     <para>The <filename>.ghci</filename> in your home directory is
     most useful for turning on favourite options (eg. <literal>:set
 
     <para>The <filename>.ghci</filename> in your home directory is
     most useful for turning on favourite options (eg. <literal>:set

@@ -2483,7 +2442,7 @@ Prelude> :set -fno-glasgow-exts
     project is a useful way to set certain project-wide options so you
     don't have to type them everytime you start GHCi: eg. if your
     project uses GHC extensions and CPP, and has source files in three
     project is a useful way to set certain project-wide options so you
     don't have to type them everytime you start GHCi: eg. if your
     project uses GHC extensions and CPP, and has source files in three

-    subdirectories A B and C, you might put the following lines in
+    subdirectories A, B and C, you might put the following lines in

     <filename>.ghci</filename>:</para>
 
 <screen>
     <filename>.ghci</filename>:</para>
 
 <screen>

@@ -2631,7 +2590,19 @@ Prelude> :set -fno-glasgow-exts
        <term>I can't use Control-C to interrupt computations in
           GHCi on Windows.</term>
         <listitem>
        <term>I can't use Control-C to interrupt computations in
           GHCi on Windows.</term>
         <listitem>

-          <para>See <xref linkend="ghci-windows"/></para>
+          <para>See <xref linkend="ghci-windows"/>.</para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+       <term>The default buffering mode is different in GHCi to GHC.</term>
+        <listitem>
+          <para>
+            In GHC, the stdout handle is line-buffered by default.
+            However, in GHCi we turn off the buffering on stdout,
+            because this is normally what you want in an interpreter:
+            output appears as it is generated.
+          </para>

         </listitem>
       </varlistentry>
     </variablelist>
         </listitem>
       </varlistentry>
     </variablelist>