I have a xml like <root> <record>Tom,20,male</record>

You can start by looking at this function forum.appian.com/.../Scripting_Functions.html

toRecord() might not help you in this instance because your XML is not well defined to map directly into the Person CDT.
What you need to do is create a RULE that takes each element (that is <record>) from this XML and tokenizes the string to get the three of the values as an array.
Then you need to use the type!person() function to build each element of your CDT
So you would do something like
type!person(name:ri!myparsedArray[0], age:ri!myparsedArray[1] ...)
Then you call this rule within an apply function and you iterate through each of the <record> element
Let me know if this is clear.