digit is predefined parser. The implementation is similar to <div><br></div><div><font class="Apple-style-span" face="&#39;courier new&#39;, monospace">digit = oneOf &quot;0123456789&quot;</font><br><br></div><div>Be sure to read carefully though. At the beginning of Chapter 2 (Parsing) it reads:</div>

<div><br></div><div><div><i>Parsec provides a number of pre-built parsers: for example, letter and <b>digit</b> are library functions.</i></div></div><div><br></div><div>Also, I recommend downloading the ebook as PDF. It is easier to read that way.</div>

<div><br></div><div>Best regards,</div><div>Krzysztof Skrzętnicki</div><div><br><div class="gmail_quote">On Sat, Apr 9, 2011 at 03:45, Michael Litchard <span dir="ltr">&lt;<a href="mailto:michael@schmong.org">michael@schmong.org</a>&gt;</span> wrote:<br>

<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">I&#39;m working through &quot;Write yourself a Scheme in 48 hours&quot;. I&#39;m on the<br>
parsing section<br>
<a href="http://en.wikibooks.org/wiki/Write_Yourself_a_Scheme_in_48_Hours/Parsing" target="_blank">http://en.wikibooks.org/wiki/Write_Yourself_a_Scheme_in_48_Hours/Parsing</a><br>
<br>
and I have a question about the following function<br>
<br>
parseNumber :: Parser LispVal<br>
parseNumber = liftM (Number . read) $ many1 digit<br>
<br>
digit looks like a variable, but I don&#39;t see it mentioned anywhere.<br>
Where is the input coming from?<br>
Is this an example of partial application?<br>
<br>
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</blockquote></div><br></div>