# PRN in range(0,n)
create or replace function prn(n) as trunc(random() * n)::BIGINT;

create or replace function list_random(lst) as
  lst[ 1 + prn(length(lst)) ] ;

## Example:
select histogram( r )
   from (select list_random( [1,2,3] ) as r from range(0,1000) _(n));