QQ - if I have an Excel spreadsheet on the classpath of a Mule app, can I do a lookup against it using dataweave alone?
In order to use excel as a lookup you need to use the readUrl function using the classpath protocol
var excel = readUrl("classpath://myExcelFile.xlsx", "application/xlsx") --- (excel.mySheet filter ((entry, index) -> entry.foo == var.foo))[0]