Atom - ŒQ - Distinct Sieve
Tags: miscellaneous , array
Arity: monadic
This atom is monadic, which means it takes one argument.
Functionality
Replace the first occurrence of each element with 1 and all subsequent ones with 0.
Details
Replicating (x) a list by the distinct sieve will uniquify the list. That is, xŒQ$ is equivalent to Q (Uniquify).