diff options
| -rw-r--r-- | docs/users_guide/glasgow_exts.xml | 82 |
1 files changed, 41 insertions, 41 deletions
diff --git a/docs/users_guide/glasgow_exts.xml b/docs/users_guide/glasgow_exts.xml index 3f78d2d853..09dd782274 100644 --- a/docs/users_guide/glasgow_exts.xml +++ b/docs/users_guide/glasgow_exts.xml @@ -933,7 +933,7 @@ rec { b <- f a c ===> (b,c) <- mfix (\~(b,c) -> do { b <- f a c ; c <- f b a } ; c <- f b a ; return (b,c) }) </programlisting> -In general, the statment <literal>rec <replaceable>ss</replaceable></literal> +In general, the statement <literal>rec <replaceable>ss</replaceable></literal> is desugared to the statement <programlisting> <replaceable>vs</replaceable> <- mfix (\~<replaceable>vs</replaceable> -> do { <replaceable>ss</replaceable>; return <replaceable>vs</replaceable> }) @@ -1028,7 +1028,7 @@ This name is not supported by GHC. [ (x, y) | x <- xs | y <- ys ] </programlisting> - <para>The behavior of parallel list comprehensions follows that of + <para>The behaviour of parallel list comprehensions follows that of zip, in that the resulting list will have the same length as the shortest branch.</para> @@ -1790,7 +1790,7 @@ the same as the omitted field names. <listitem><para> The "<literal>..</literal>" expands to the missing -<emphasis>in-scope</emphasis> record fields. +<emphasis>in-scope</emphasis> record fields. Specifically the expansion of "<literal>C {..}</literal>" includes <literal>f</literal> if and only if: <itemizedlist> @@ -1801,8 +1801,8 @@ Specifically the expansion of "<literal>C {..}</literal>" includes The record field <literal>f</literal> is in scope somehow (either qualified or unqualified). </para></listitem> <listitem><para> -In the case of expressions (but not patterns), -the variable <literal>f</literal> is in scope unqualified, +In the case of expressions (but not patterns), +the variable <literal>f</literal> is in scope unqualified, apart from the binding of the record selector itself. </para></listitem> </itemizedlist> @@ -1817,7 +1817,7 @@ module X where The <literal>R{..}</literal> expands to <literal>R{M.a=a}</literal>, omitting <literal>b</literal> since the record field is not in scope, and omitting <literal>c</literal> since the variable <literal>c</literal> -is not in scope (apart from the binding of the +is not in scope (apart from the binding of the record selector <literal>c</literal>, of course). </para></listitem> </itemizedlist> @@ -2060,7 +2060,7 @@ The following syntax is stolen: <sect2 id="nullary-types"> <title>Data types with no constructors</title> -<para>With the <option>-XEmptyDataDecls</option> flag (or equivalent LANGUAGE pragma), +<para>With the <option>-XEmptyDataDecls</option> flag (or equivalent LANGUAGE pragma), GHC lets you declare a data type with no constructors. For example:</para> <programlisting> @@ -3535,7 +3535,7 @@ liberal in these case. For example, this is OK: <programlisting> class A cls c where meth :: cls c => c -> c - + class A B c => B c where </programlisting> @@ -4260,7 +4260,7 @@ of the instance declaration, thus: </para> <para> Warning: overlapping instances must be used with care. They -can give rise to incoherence (ie different instance choices are made +can give rise to incoherence (i.e. different instance choices are made in different parts of the program) even without <option>-XIncoherentInstances</option>. Consider: <programlisting> {-# LANGUAGE OverlappingInstances #-} @@ -4839,7 +4839,7 @@ instance (Eq (Elem [e])) => Collects ([e]) where type indexes corresponding to class parameters must be identical to the type given in the instance head; here this is the first argument of <literal>GMap</literal>, namely <literal>Either a b</literal>, - which coincides with the only class parameter. + which coincides with the only class parameter. </para> <para> Instances for an associated family can only appear as part of @@ -4873,7 +4873,7 @@ instance GMapKey Flob where <sect3 id="assoc-decl-defs"> <title>Associated type synonym defaults</title> <para> - It is possible for the class defining the associated type to specify a + It is possible for the class defining the associated type to specify a default for associated type instances. So for example, this is OK: <programlisting> class IsBoolMap v where @@ -4905,7 +4905,7 @@ A default declaration is not permitted for an associated <para> The visibility of class parameters in the right-hand side of associated family instances - depends <emphasis>solely</emphasis> on the parameters of the + depends <emphasis>solely</emphasis> on the parameters of the family. As an example, consider the simple class declaration <programlisting> class C a b where @@ -4929,19 +4929,19 @@ instance C [c] d where <title>Import and export</title> <para> -The rules for export lists -(Haskell Report +The rules for export lists +(Haskell Report <ulink url="http://www.haskell.org/onlinereport/modules.html#sect5.2">Section 5.2</ulink>) needs adjustment for type families: <itemizedlist> <listitem><para> The form <literal>T(..)</literal>, where <literal>T</literal> - is a data family, names the family <literal>T</literal> and all the in-scope - constructors (whether in scope qualified or unqualified) that are data + is a data family, names the family <literal>T</literal> and all the in-scope + constructors (whether in scope qualified or unqualified) that are data instances of <literal>T</literal>. </para></listitem> <listitem><para> - The form <literal>T(.., ci, .., fj, ..)</literal>, where <literal>T</literal> is + The form <literal>T(.., ci, .., fj, ..)</literal>, where <literal>T</literal> is a data family, names <literal>T</literal> and the specified constructors <literal>ci</literal> and fields <literal>fj</literal> as usual. The constructors and field names must belong to some data instance of <literal>T</literal>, but are not required to belong @@ -4974,7 +4974,7 @@ class GMapKey k where instance (GMapKey a, GMapKey b) => GMapKey (Either a b) where data GMap (Either a b) v = GMapEither (GMap a v) (GMap b v) - ...method declartions... + ...method declarations... </programlisting> Here are some export lists and their meaning: <itemizedlist> @@ -4991,21 +4991,21 @@ Here are some export lists and their meaning: (in this case <literal>GMapEither</literal>) are not exported.</para> </listitem> <listitem> - <para><literal>module GMap( GMapKey( type GMap, empty, lookup, insert ) )</literal>: - Same as the pevious item. Note the "<literal>type</literal>" keyword.</para> + <para><literal>module GMap( GMapKey( type GMap, empty, lookup, insert ) )</literal>: + Same as the previous item. Note the "<literal>type</literal>" keyword.</para> </listitem> <listitem> - <para><literal>module GMap( GMapKey(..), GMap(..) )</literal>: + <para><literal>module GMap( GMapKey(..), GMap(..) )</literal>: Same as previous item, but also exports all the data constructors for <literal>GMap</literal>, namely <literal>GMapEither</literal>. </para> </listitem> <listitem> - <para><literal>module GMap ( GMapKey( empty, lookup, insert), GMap(..) )</literal>: + <para><literal>module GMap ( GMapKey( empty, lookup, insert), GMap(..) )</literal>: Same as previous item.</para> </listitem> <listitem> - <para><literal>module GMap ( GMapKey, empty, lookup, insert, GMap(..) )</literal>: + <para><literal>module GMap ( GMapKey, empty, lookup, insert, GMap(..) )</literal>: Same as previous item.</para> </listitem> </itemizedlist> @@ -5022,16 +5022,16 @@ Two things to watch out for: <listitem><para> Consider this example: <programlisting> - module X where + module X where data family D module Y where import X data instance D Int = D1 | D2 </programlisting> - Module Y exports all the entities defined in Y, namely the data constructrs <literal>D1</literal> + Module Y exports all the entities defined in Y, namely the data constructors <literal>D1</literal> and <literal>D2</literal>, <emphasis>but not the data family <literal>D</literal></emphasis>. - That (annoyingly) means that you cannot selectively import Y selectively, + That (annoyingly) means that you cannot selectively import Y selectively, thus "<literal>import Y( D(D1,D2) )</literal>", because Y does not export <literal>D</literal>. Instead you should list the exports explicitly, thus: <programlisting> @@ -5040,7 +5040,7 @@ or module Y( module Y, D ) where ... </programlisting> </para></listitem> </itemizedlist> -</para> +</para> </sect3> <sect3 id="data-family-impexp-instances"> @@ -5081,7 +5081,7 @@ The situation is especially bad because the type instance for <literal>F Bool</l might be in another module, or even in a module that is not yet written. </para> <para> -However, type class instances of instances of data families can be defined +However, type class instances of instances of data families can be defined much like any other data type. For example, we can say <programlisting> data instance T Int = T1 Int | T2 Bool @@ -5228,7 +5228,7 @@ foo x = (show x, read) </para> <programlisting> -type family Clsish u a +type family Clsish u a type instance Clsish () a = Cls a class Clsish () a => Cls a where </programlisting> @@ -5236,7 +5236,7 @@ class Clsish () a => Cls a where <programlisting> class OkCls a where -type family OkClsish u a +type family OkClsish u a type instance OkClsish () a = OkCls a instance OkClsish () a => OkCls a where </programlisting> @@ -6879,10 +6879,10 @@ The quoted <replaceable>string</replaceable> finishes at the first occurrence of the two-character sequence <literal>"|]"</literal>. Absolutely no escaping is performed. If you want to embed that character sequence in the string, you must invent your own escape convention (such -as, say, using the string <literal>"|~]"</literal> instead), and make your +as, say, using the string <literal>"|~]"</literal> instead), and make your quoter function interpret <literal>"|~]"</literal> as <literal>"|]"</literal>. One way to implement this is to compose your quoter with a pre-processing pass to -perform your escape conversion. See the +perform your escape conversion. See the <ulink url="http://hackage.haskell.org/trac/ghc/ticket/5348"> discussion in Trac</ulink> for details. </para></listitem> @@ -8305,7 +8305,7 @@ happen. <itemizedlist> <listitem> <para>A <literal>SPECIALIZE</literal> pragma for a function can - be put anywhere its type signature could be put. Moreover, you + be put anywhere its type signature could be put. Moreover, you can also <literal>SPECIALIZE</literal> an <emphasis>imported</emphasis> function provided it was given an <literal>INLINABLE</literal> pragma at its definition site (<xref linkend="inlinable-pragma"/>).</para> @@ -8325,9 +8325,9 @@ happen. </listitem> <listitem> - <para>You can add phase control (<xref linkend="phase-control"/>) + <para>You can add phase control (<xref linkend="phase-control"/>) to the RULE generated by a <literal>SPECIALIZE</literal> pragma, - just as you can if you writ a RULE directly. For exxample: + just as you can if you write a RULE directly. For example: <programlisting> {-# SPECIALIZE [0] hammeredLookup :: [(Widget, value)] -> Widget -> value #-} </programlisting> @@ -8342,12 +8342,12 @@ happen. {-# SPECIALIZE foo :: Int -> Int #-} </programlisting> The <literal>NOINLINE</literal> pragma tells GHC not to inline <literal>foo</literal> - until Phase 0; and this property is inherited by the specialiation RULE, which will + until Phase 0; and this property is inherited by the specialisation RULE, which will therefore only fire in Phase 0.</para> - <para>The main reason for using phase control on specialisations is so that you can - write optimisation RULES that fire early in the compilation pipeline, and only + <para>The main reason for using phase control on specialisations is so that you can + write optimisation RULES that fire early in the compilation pipeline, and only <emphasis>then</emphasis> specialise the calls to the function. If specialisation is - done too early, the optimsation rules might fail to fire. + done too early, the optimisation rules might fail to fire. </para> </listitem> @@ -8411,9 +8411,9 @@ the specialised function will be inlined. It has two calls to both at type <literal>Int</literal>. Both these calls fire the first specialisation, whose body is also inlined. The result is a type-based unrolling of the indexing function.</para> -<para>You can add explicit phase control (<xref linkend="phase-control"/>) +<para>You can add explicit phase control (<xref linkend="phase-control"/>) to <literal>SPECIALISE INLINE</literal> pragma, -just like on an <literal>INLINE</literal> pragma; if you do so, the same phase +just like on an <literal>INLINE</literal> pragma; if you do so, the same phase is used for the rewrite rule and the INLINE control of the specialised function.</para> <para>Warning: you can make GHC diverge by using <literal>SPECIALISE INLINE</literal> |