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copied!<p>If you want to know where the range stops, just get the last item…</p> <pre><code>ghci> last ['a'.. ] '\1114111' </code></pre> <p>Another method: <code>Char</code> is a bounded type, i.e. a type with minimum and maximum values defined. Types in the <code>Bounded</code> class provide a <code>maxBound</code> value. Since <code>maxBound</code> is polymorphic, you have to explicitly state the type of the value you're looking for.</p> <pre><code>ghci> maxBound :: Char '\1114111' ghci> maxBound :: Int 9223372036854775807 </code></pre> <p>There is no <code>maxBound</code> for <code>Integer</code> since they are unbounded.</p> <p>The <a href="http://www.haskell.org/ghc/docs/latest/html/libraries/base/Prelude.html#t%3aEnum">Haskell prelude</a> explains the connection between <code>['a'..]</code> and <code>maxBound</code>. The notation <code>['a'..]</code> is syntactic sugar for <code>enumFrom a</code>; here <code>enumFrom</code> is a method of the <code>Enum</code> type class. The documentation of <code>Enum</code> specifies that when the type is also an instance of <code>Bounded</code>, <code>enumFrom x</code> should be equivalent to <code>enumFromTo x maxBound</code>, or more readably, <code>[x..] = [x..maxBound]</code>. So the last element of <code>['a'..]</code> must be the same as <code>maxBound :: Char</code>. </p> <p><code>last ['a'.. ]</code> does iterate over the list, but a modern computer can count to a million in an eyeblink. It's not something you would want to put in a tight loop, but as something you run just once it isn't a big burden. If you try it out in a less optimized implementation such as Hugs instead of GHC, you may need to wait for the result. In contrast <code>last [0..]</code> would take approximately forever.</p>

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