Concatenate URL in XSL

I'm trying to concatenate a url together in xsl. Basically, I'm taking two variables and incorporating those into the pieces of the link to开发者_JAVA百科 make things dynamic. How can I perform this concatenation?

<a href="{concat('http://',$string1,'/',$string2)}>link</a>

Depends on the variables and on the target URL, but you want to use concat() anyway.