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author | Ian Lynagh <igloo@earth.li> | 2007-07-16 23:17:41 +0000 |
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committer | Ian Lynagh <igloo@earth.li> | 2007-07-16 23:17:41 +0000 |
commit | 8fdc756d38495bf89d110d0d4869300673f91a08 (patch) | |
tree | dda253aeacecc2825ac45526dc97bb75feeefa48 /docs | |
parent | dbbc561d4599b647b9256bc893b425556fdb5e84 (diff) | |
download | haskell-8fdc756d38495bf89d110d0d4869300673f91a08.tar.gz |
Corrections for warnings in the user guide
Diffstat (limited to 'docs')
-rw-r--r-- | docs/users_guide/using.xml | 36 |
1 files changed, 21 insertions, 15 deletions
diff --git a/docs/users_guide/using.xml b/docs/users_guide/using.xml index eedc9e112b..c24a20c3c9 100644 --- a/docs/users_guide/using.xml +++ b/docs/users_guide/using.xml @@ -878,6 +878,20 @@ ghc -c Foo.hs</screen> function or type is used. Entities can be marked as deprecated using a pragma, see <xref linkend="deprecated-pragma"/>.</para> + + <para>This option is on by default.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>-fwarn-dodgy-imports</option>:</term> + <listitem> + <indexterm><primary><option>-fwarn-dodgy-imports</option></primary> + </indexterm> + <para>Causes a warning to be emitted when a a datatype + <literal>T</literal> is imported + with all constructors, i.e. <literal>T(..)</literal>, but has been + exported abstractly, i.e. <literal>T</literal>.</para> </listitem> </varlistentry> @@ -954,7 +968,7 @@ ghc -c Foo.hs</screen> g [] = 2 </programlisting> - <para>This option isn't enabled be default because it can be + <para>This option isn't enabled by default because it can be a bit noisy, and it doesn't always indicate a bug in the program. However, it's generally considered good practice to cover all the cases in your functions.</para> @@ -982,7 +996,7 @@ f :: Foo -> Foo f foo = foo { x = 6 } </programlisting> - <para>This option isn't enabled be default because it can be + <para>This option isn't enabled by default because it can be very noisy, and it often doesn't indicate a bug in the program.</para> </listitem> @@ -1055,12 +1069,8 @@ f foo = foo { x = 6 } inner-scope value has the same name as an outer-scope value, i.e. the inner value shadows the outer one. This can catch typographical errors that turn into hard-to-find bugs, e.g., - in the inadvertent cyclic definition <literal>let x = ... x - ... in</literal>.</para> - - <para>Consequently, this option - <emphasis>will</emphasis> complain about cyclic recursive - definitions.</para> + in the inadvertent capture of what would be a recursive call in + <literal>f = ... let f = id in ... f ...</literal>.</para> </listitem> </varlistentry> @@ -1094,7 +1104,7 @@ f foo = foo { x = 6 } </term> <listitem> <para>By default, the compiler will warn you if a set of - patterns are overlapping, i.e.,</para> + patterns are overlapping, e.g.,</para> <programlisting> f :: String -> Int @@ -1119,7 +1129,7 @@ f "2" = 2 patterns that can fail, eg. <literal>\(x:xs)->...</literal>. Normally, these aren't treated as incomplete patterns by <option>-fwarn-incomplete-patterns</option>.</para> - <para>``Lambda-bound patterns'' includes all places where there is a single pattern, + <para>“Lambda-bound patterns” includes all places where there is a single pattern, including list comprehensions and do-notation. In these cases, a pattern-match failure is quite legitimate, and triggers filtering (list comprehensions) or the monad <literal>fail</literal> operation (monads). For example: @@ -1129,10 +1139,6 @@ f "2" = 2 </programlisting> Switching on <option>-fwarn-simple-patterns</option> will elicit warnings about these probably-innocent cases, which is why the flag is off by default. </para> - <para> The <literal>deriving( Read )</literal> mechanism produces monadic code with - pattern matches, so you will also get misleading warnings about the compiler-generated - code. (This is arguably a Bad Thing, but it's awkward to fix.)</para> - </listitem> </varlistentry> @@ -1157,7 +1163,7 @@ f "2" = 2 the Haskell defaulting mechanism for numeric types kicks in. This is useful information when converting code from a context that assumed one default into one with another, - e.g., the `default default' for Haskell 1.4 caused the + e.g., the ‘default default’ for Haskell 1.4 caused the otherwise unconstrained value <constant>1</constant> to be given the type <literal>Int</literal>, whereas Haskell 98 defaults it to <literal>Integer</literal>. This may lead to |