Editing Common Lisp (section)

===Scalar types===
''Number'' types include [[integer]]s, [[ratio]]s, [[floating-point arithmetic|floating-point number]]s, and [[complex number]]s.<ref name="reddy">{{cite web
 |url=http://random-state.net/features-of-common-lisp.html
 |title=Features of Common Lisp
 |first=Abhishek |last=Reddy
 |date=August 22, 2008
}}</ref> Common Lisp uses [[Arbitrary-precision arithmetic|bignum]]s to represent numerical values of arbitrary size and precision. The ratio type represents fractions exactly, a facility not available in many languages. Common Lisp automatically coerces numeric values among these types as appropriate.

The Common Lisp ''[[character (computing)|character]]'' type is not limited to [[ASCII]] characters. Most modern implementations allow [[Unicode]] characters.<ref>{{cite web
 |url=http://www.cliki.net/Unicode%20Support
 |title=Unicode support |work=The Common Lisp Wiki |access-date=August 21, 2008
}}</ref>

The ''[[Symbol (programming)|symbol]]'' type is common to Lisp languages, but largely unknown outside them. A symbol is a unique, named data object with several parts: name, value, function, property list, and package. Of these, ''value cell'' and ''function cell'' are the most important. Symbols in Lisp are often used similarly to identifiers in other languages: to hold the value of a variable; however there are many other uses. Normally, when a symbol is evaluated, its value is returned. Some symbols evaluate to themselves, for example, all symbols in the keyword package are self-evaluating. Boolean values in Common Lisp are represented by the self-evaluating symbols T and NIL. Common Lisp has namespaces for symbols, called 'packages'.

A number of functions are available for [[rounding]] scalar numeric values in various ways. The function <code>round</code> rounds the argument to the nearest integer, with halfway cases rounded to the even integer. The functions <code>truncate</code>, <code>floor</code>, and <code>ceiling</code> round towards zero, down, or up respectively.  All these functions return the discarded fractional part as a secondary value. For example, <code>(floor -2.5)</code> yields −3, 0.5; <code>(ceiling -2.5)</code> yields −2, −0.5; <code>(round 2.5)</code> yields 2, 0.5; and <code>(round 3.5)</code> yields 4, −0.5.