nemunaire-overlay/dev-haskell/scientific/metadata.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE pkgmetadata SYSTEM "http://www.gentoo.org/dtd/metadata.dtd">
<pkgmetadata>
	<maintainer type="project">
		<email>haskell@gentoo.org</email>
		<name>Gentoo Haskell</name>
	</maintainer>
	<longdescription>
		&quot;Data.Scientific&quot; provides the number type &#39;Scientific&#39;. Scientific numbers are
		arbitrary precision and space efficient. They are represented using
		&lt;http://en.wikipedia.org/wiki/Scientific_notation scientific notation&gt;.
		The implementation uses a coefficient @c :: &#39;Integer&#39;@ and a base-10 exponent
		@e :: &#39;Int&#39;@. A scientific number corresponds to the
		&#39;Fractional&#39; number: @&#39;fromInteger&#39; c * 10 &#39;^^&#39; e@.
		
		Note that since we&#39;re using an &#39;Int&#39; to represent the exponent these numbers
		aren&#39;t truly arbitrary precision. I intend to change the type of the exponent
		to &#39;Integer&#39; in a future release.
		
		The main application of &#39;Scientific&#39; is to be used as the target of parsing
		arbitrary precision numbers coming from an untrusted source. The advantages
		over using &#39;Rational&#39; for this are that:
		
		* A &#39;Scientific&#39; is more efficient to construct. Rational numbers need to be
		constructed using &#39;%&#39; which has to compute the &#39;gcd&#39; of the &#39;numerator&#39; and
		&#39;denominator&#39;.
		
		* &#39;Scientific&#39; is safe against numbers with huge exponents. For example:
		@1e1000000000 :: &#39;Rational&#39;@ will fill up all space and crash your
		program. Scientific works as expected:
		
		&gt;&gt;&gt; read &quot;1e1000000000&quot; :: Scientific
		1.0e1000000000
		
		* Also, the space usage of converting scientific numbers with huge exponents to
		@&#39;Integral&#39;s@ (like: &#39;Int&#39;) or @&#39;RealFloat&#39;s@ (like: &#39;Double&#39; or &#39;Float&#39;)
		will always be bounded by the target type.
	</longdescription>
</pkgmetadata>