indicate that the current context for expressions typed at the
prompt is the <literal>Main</literal> module we just loaded (we'll
explain what the <literal>*</literal> means later in <xref
- linkend="ghci-scope">). So we can now type expressions involving
+ linkend="ghci-scope"/>). So we can now type expressions involving
the functions from <filename>Main.hs</filename>:</para>
<screen>
<para>or it can be set using the <literal>:set</literal> command
from within GHCi (see <xref
- linkend="ghci-cmd-line-options">)<footnote><para>Note that in
+ linkend="ghci-cmd-line-options"/>)<footnote><para>Note that in
GHCi, and <option>––make</option> mode, the <option>-i</option>
option is used to specify the search path for
<emphasis>source</emphasis> files, whereas in standard
batch-compilation mode the <option>-i</option> option is used to
specify the search path for interface files, see <xref
- linkend="search-path">.</para> </footnote></para>
+ linkend="search-path"/>.</para> </footnote></para>
<para>One consequence of the way that GHCi follows dependencies
to find modules to load is that every module must have a source
doing its best to avoid actually recompiling modules if their
external dependencies haven't changed. This is the same
mechanism we use to avoid re-compiling modules in the batch
- compilation setting (see <xref linkend="recomp">).</para>
+ compilation setting (see <xref linkend="recomp"/>).</para>
</sect2>
</sect1>
use one in preference to interpreting the source if possible. For
example, suppose we have a 4-module program consisting of modules
A, B, C, and D. Modules B and C both import D only,
- and A imports both B & C:</para>
+ and A imports both B & C:</para>
<screen>
A
/ \
<para>Here's an example:</para>
<screen>
-Prelude> x <- return 42
+Prelude> x <- return 42
Prelude> print x
42
Prelude>
</screen>
- <para>The statement <literal>x <- return 42</literal> means
+ <para>The statement <literal>x <- return 42</literal> means
“execute <literal>return 42</literal> in the
<literal>IO</literal> monad, and bind the result to
<literal>x</literal>”. We can then use
Prelude>
</screen>
<para>An important difference between the two types of binding
- is that the monadic bind (<literal>p <- e</literal>) is
+ is that the monadic bind (<literal>p <- e</literal>) is
<emphasis>strict</emphasis> (it evaluates <literal>e</literal>),
whereas with the <literal>let</literal> form, the expression
isn't evaluated immediately:</para>
<para>The corresponding translation for an IO-typed
<replaceable>e</replaceable> is
<screen>
- it <- <replaceable>e</replaceable>
+ it <- <replaceable>e</replaceable>
</screen>
</para>
instructs GHCi to load the specified modules or filenames (and all
the modules they depend on), just as if you had said
<literal>:load <replaceable>modules</replaceable></literal> at the
- GHCi prompt (see <xref linkend="ghci-commands">). For example, to
+ GHCi prompt (see <xref linkend="ghci-commands"/>). For example, to
start GHCi and load the program whose topmost module is in the
file <literal>Main.hs</literal>, we could say:</para>
</screen>
<para>Most of the command-line options accepted by GHC (see <xref
- linkend="using-ghc">) also make sense in interactive mode. The ones
+ 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>
<title>Packages</title>
<indexterm><primary>packages</primary><secondary>with GHCi</secondary></indexterm>
- <para>Most packages (see <xref linkend="using-packages">) are
+ <para>Most packages (see <xref linkend="using-packages"/>) are
available without needing to specify any extra flags at all:
they will be automatically loaded the first time they are
needed.</para>
the normal <literal>-l<replaceable>lib</replaceable></literal>
option. (The term <emphasis>library</emphasis> here refers to
libraries of foreign object code; for using libraries of Haskell
- source code, see <xref linkend="ghci-modules-filenames">.) For
+ source code, see <xref linkend="ghci-modules-filenames"/>.) For
example, to load the “m” library:</para>
<screen>
<para>Ordering of <option>-l</option> options matters: a library
should be mentioned <emphasis>before</emphasis> the libraries it
- depends on (see <xref linkend="options-linker">).</para>
+ depends on (see <xref linkend="options-linker"/>).</para>
</sect2>
</sect1>
<para>That's all a little confusing, so here's a few
examples. To start with, here's a new GHCi command which
doesn't take any arguments or produce any results, it just
- outputs the current date & time:</para>
+ outputs the current date & time:</para>
<screen>
Prelude> let date _ = Time.getClockTime >>= print >> return ""
<indexterm><primary><literal>:module</literal></primary></indexterm>
<listitem>
<para>Sets or modifies the current context for statements
- typed at the prompt. See <xref linkend="ghci-scope"> for
+ typed at the prompt. See <xref linkend="ghci-scope"/> for
more details.</para>
</listitem>
</varlistentry>
<term><literal>:set</literal> <optional><replaceable>option</replaceable>...</optional></term>
<indexterm><primary><literal>:set</literal></primary></indexterm>
<listitem>
- <para>Sets various options. See <xref linkend="ghci-set">
+ <para>Sets various options. See <xref linkend="ghci-set"/>
for a list of available options. The
<literal>:set</literal> command by itself shows which
options are currently set.</para>
<term><literal>:unset</literal> <replaceable>option</replaceable>...</term>
<indexterm><primary><literal>:unset</literal></primary></indexterm>
<listitem>
- <para>Unsets certain options. See <xref linkend="ghci-set">
+ <para>Unsets certain options. See <xref linkend="ghci-set"/>
for a list of available options.</para>
</listitem>
</varlistentry>
<para>Any GHC command-line option that is designated as
<firstterm>dynamic</firstterm> (see the table in <xref
- linkend="flag-reference">), may be set using
+ linkend="flag-reference"/>), may be set using
<literal>:set</literal>. To unset an option, you can set the
reverse option:</para>
<indexterm><primary>dynamic</primary><secondary>options</secondary></indexterm>
Prelude> :set -fno-glasgow-exts
</screen>
- <para><xref linkend="flag-reference"> lists the reverse for each
+ <para><xref linkend="flag-reference"/> lists the reverse for each
option where applicable.</para>
<para>Certain static options (<option>-package</option>,
projects / ghc-hetmet.git / blobdiff