JSP 2.0 Expression Language - Functions

An upgrade from the JSTL expression language, the JSP 2.0 EL also allows for simple function invocation. Functions are defined by tag libraries and are implemented by a Java programmer as static methods.
Change Parameter
foo =

EL Expression Result
${param["foo"]}  
${my:reverse(param["foo"])}  
${my:reverse(my:reverse(param["foo"]))}  
${my:countVowels(param["foo"])} 0