src/doc/pragmas.html

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<h1>Pragmas</h1>

Hbc implements the following pragmas:
<ul>
  <li>STRICT<p>
Force strict evaluation of an expression.
For example
<pre>
        f x ((y+1){-#STRICT#-})
</pre>
forces evaluation of <tt>y+1</tt> before the call of <tt>f</tt>.
<p>

  <li>SPECIALIZE<p>
<pre>
  {-# SPECIALIZE f :: T, ...}
</pre>
Specialize the function <tt>t</tt> to the type(s) <tt>T</tt>.  For example
<pre>
  {-# SPECIALIZE inc :: Int->Int, Double->Double #-}
  inc x = x + 1
</pre>
will give the usual overloaded version of <tt>inc</tt>, but also versions 
specialized to the types Int and Double.  The specialized instances are used 
whereever the typechecker can determine (statically) that the specialized type 
occurs.
<p>
  <li>SPECIALIZE instance<p>
<pre>
  {-# SPECIALIZE instance C T #-}
</pre>
Specialize an instance declaration to a particular type.

Suitable specializations have been inserted for a lot of functions and instances
in the standard prelude to improve efficiency.
<p>

  <li>COMPILERFLAGS flag ...<p>
If this pragma is given on the first line of a file the flags
are decoded as ordinary compiler flags.
<p>
</ul>

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<address></address>
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Last modified: Sun Sep  8 00:46:46 MET DST 1996
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