Alex,

You can check this link : Jelly: Over and Over Again...

Also, the code will be something like:

//impArr1 is the Array name

<j:forEach var="jvar_pair" items="$[impArr1]" indexVar="jvar_i">

<g:evaluate var="jvar_cat" expression="var sp = $[jvar_index]; sp;" />

$[javr_cat]

</j:forEach>