Add -XBinaryLiterals language extension (re #9224)

Haskell2010 supports

- base-10 (prefix-less),
- base-8 (via `0[oO]`-prefix), and
- base-16 (via `0[xX]`-prefix) integer literals.

This commit adds syntax support for base-2 integer literals via the new `0[bB]`
prefix. The use of a `0b` prefix for indicating binary literals is known
from popular programming languages such as C++14, Perl, Python, Ruby, and Java.

This syntax extension is disabled by default and can be enabled via the
new `{-# LANGUAGE BinaryLiterals #-}` pragma and/or the new `-XBinaryLiterals`

This new extensions requires to upgrade the `ExtsBitmap` type from
`Word` to `Word64` as this adds a 33th flag which is not guaranteed to
fit into a `Word`.

Signed-off-by: Herbert Valerio Riedel <hvr@gnu.org>

Differential Revision: https://phabricator.haskell.org/D22

3 files changed, 27 insertions, 1 deletions

diff --git a/docs/users_guide/7.10.1-notes.xml b/docs/users_guide/7.10.1-notes.xml
index c462a4dab4..b45721cd7b 100644
--- a/docs/users_guide/7.10.1-notes.xml
+++ b/docs/users_guide/7.10.1-notes.xml
@@ -31,7 +31,7 @@
         <itemizedlist>
             <listitem>
                 <para>
-                    TODO FIXME
+                    Added support for <link linkend="binary-literals">binary integer literals</link>
                </para>
            </listitem>
        </itemizedlist>
diff --git a/docs/users_guide/flags.xml b/docs/users_guide/flags.xml
index ad9c44c44b..1dd224a611 100644
--- a/docs/users_guide/flags.xml
+++ b/docs/users_guide/flags.xml
@@ -763,6 +763,12 @@
             <entry><option>-XNoBangPatterns</option></entry>
           </row>
           <row>
+            <entry><option>-XBinaryLiterals</option></entry>
+            <entry>Enable support for <link linkend="binary-literals">binary literals</link>.</entry>
+            <entry>dynamic</entry>
+            <entry><option>-XNoBinaryLiterals</option></entry>
+          </row>
+          <row>
             <entry><option>-XCApiFFI</option></entry>
             <entry>Enable <link linkend="ffi-capi">the CAPI calling convention</link>.</entry>
             <entry>dynamic</entry>
diff --git a/docs/users_guide/glasgow_exts.xml b/docs/users_guide/glasgow_exts.xml
index e959a1f2ab..e97d5798fe 100644
--- a/docs/users_guide/glasgow_exts.xml
+++ b/docs/users_guide/glasgow_exts.xml
@@ -480,6 +480,26 @@ Indeed, the bindings can even be recursive.
       </para>
    </sect2>
 
+    <sect2 id="binary-literals">
+      <title>Binary integer literals</title>
+      <para>
+          Haskell 2010 and Haskell 98 allows for integer literals to
+          be given in decimal, octal (prefixed by
+          <literal>0o</literal> or <literal>0O</literal>), or
+          hexadecimal notation (prefixed by <literal>0x</literal> or
+          <literal>0X</literal>).
+      </para>
+
+      <para>
+          The language extension <option>-XBinaryLiterals</option>
+          adds support for expressing integer literals in binary
+          notation with the prefix <literal>0b</literal> or
+          <literal>0B</literal>. For instance, the binary integer
+          literal <literal>0b11001001</literal> will be desugared into
+          <literal>fromInteger 201</literal> when
+          <option>-XBinaryLiterals</option> is enabled.
+      </para>
+   </sect2>
 
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