diff options
Diffstat (limited to 'docs/users_guide/ghci.xml')
| -rw-r--r-- | docs/users_guide/ghci.xml | 40 |
1 files changed, 29 insertions, 11 deletions
diff --git a/docs/users_guide/ghci.xml b/docs/users_guide/ghci.xml index a1271e1ac1..399cda90ea 100644 --- a/docs/users_guide/ghci.xml +++ b/docs/users_guide/ghci.xml @@ -674,13 +674,13 @@ Prelude> <title>What's really in scope at the prompt?</title> <para>When you type an expression at the prompt, what - identifiers and types are in scope? + identifiers and types are in scope? GHCi provides a flexible way to control exactly how the context for an expression is constructed: <itemizedlist> <listitem><para> - The <literal>:load</literal>, <literal>:add</literal>, + The <literal>:load</literal>, <literal>:add</literal>, and <literal>:reload</literal> commands (<xref linkend="ghci-load-scope"/>). </para></listitem> <listitem><para> @@ -702,8 +702,8 @@ Prelude> <sect3 id="ghci-load-scope"> <title>The effect of <literal>:load</literal> on what is in scope</title> <para> - The <literal>:load</literal>, <literal>:add</literal>, and <literal>:reload</literal> - commands (<xref linkend="loading-source-files"/> + The <literal>:load</literal>, <literal>:add</literal>, and <literal>:reload</literal> + commands (<xref linkend="loading-source-files"/> and <xref linkend="ghci-compiled"/>) affect the top-level scope. Let's start with the simple cases; when you start GHCi the prompt looks like this: @@ -830,7 +830,7 @@ Prelude System.IO Map> <title>Controlling what is in scope with the <literal>:module</literal> command</title> <para>Another way to manipulate the scope is to use the - <literal>:module</literal> command, whose syntax is this: + <literal>:module</literal> command, whose syntax is this: <screen> :module <optional>+|-</optional> <optional>*</optional><replaceable>mod<subscript>1</subscript></replaceable> ... <optional>*</optional><replaceable>mod<subscript>n</subscript></replaceable> @@ -881,7 +881,7 @@ Prelude System.IO Map> <literal>:load</literal></title> <para>It might seem that <literal>:module</literal>/<literal>import</literal> and - <literal>:load</literal>/<literal>:add</literal>/<literal>:reload</literal> + <literal>:load</literal>/<literal>:add</literal>/<literal>:reload</literal> do similar things: you can use both to bring a module into scope. However, there is a very important difference. GHCi is concerned with two sets of modules:</para> @@ -907,7 +907,7 @@ Prelude System.IO Map> </listitem> </itemizedlist> - <para>You can add a module to the scope (via <literal>:module</literal> + <para>You can add a module to the scope (via <literal>:module</literal> or <literal>import</literal>) only if either (a) it is loaded, or (b) it is a module from a package that GHCi knows about. @@ -2627,7 +2627,7 @@ T Int :: * -> * <varlistentry> <term> - <literal>:load</literal> <optional><literal>*</literal></optional><replaceable>module</replaceable> ... + <literal>:load</literal><optional><literal>!</literal></optional> <optional><literal>*</literal></optional><replaceable>module</replaceable> ... <indexterm><primary><literal>:load</literal></primary></indexterm> </term> <listitem> @@ -2649,6 +2649,15 @@ T Int :: * -> * byte-code. Using the <literal>*</literal> prefix forces a module to be loaded as byte-code.</para> + <para>Adding the optional "<literal>!</literal>" turns type + errors into warnings while loading. This allows to use the + portions of the module that are correct, even if there are + type errors in some definitions. Effectively, the + "-fdefer-type-errors" flag is set before loading and unset + after loading if the flag has not already been set + before. See <xref linkend="defer-type-errors" /> for further + motivation and details.</para> + <para>After a <literal>:load</literal> command, the current context is set to:</para> @@ -2785,7 +2794,7 @@ bar <varlistentry> <term> - <literal>:reload</literal> + <literal>:reload</literal><optional><literal>!</literal></optional> <indexterm><primary><literal>:reload</literal></primary></indexterm> </term> <listitem> @@ -2794,6 +2803,15 @@ bar or any dependent module, has changed. Note that this may entail loading new modules, or dropping modules which are no longer indirectly required by the target.</para> + + <para>Adding the optional "<literal>!</literal>" turns type + errors into warnings while loading. This allows to use the + portions of the module that are correct, even if there are + type errors in some definitions. Effectively, the + "-fdefer-type-errors" flag is set before loading and unset + after loading if the flag has not already been set + before. See <xref linkend="defer-type-errors" /> for further + motivation and details.</para> </listitem> </varlistentry> @@ -3302,7 +3320,7 @@ Prelude> :set -fno-warn-incomplete-patterns -XNoMultiParamTypeClasses <title>Setting options for interactive evaluation only</title> <para> - GHCi actually maintains <emphasis>two</emphasis> sets of options: + GHCi actually maintains <emphasis>two</emphasis> sets of options: <itemizedlist> <listitem><para> The <emphasis>loading options</emphasis> apply when loading modules @@ -3317,7 +3335,7 @@ The <literal>:set</literal> command modifies both, but there is </para> <para> - It is often useful to change the interactive options, + It is often useful to change the interactive options, without having that option apply to loaded modules too. For example <screen> |