Basic PL/Ruby example

find_or_create_instructions.sql

/*
 * FUNCTION coleoptera.find_or_create_instructions(
 *   TEXT[] -- instruction labels
 * )
 * RETURNS coleoptera.instructions[]
 */

-- as plpgsql
CREATE OR REPLACE
  FUNCTION coleoptera.find_or_create_instructions(IN TEXT[], OUT coleoptera.instructions[])
  RETURNS coleoptera.instructions[]
  LANGUAGE PLPGSQL VOLATILE
  AS $BODY$
    BEGIN
      IF ARRAY_LOWER($1, 1) IS NULL THEN
        RETURN;
      END IF;

      FOR xIndex IN ARRAY_LOWER($1, 1) .. ARRAY_UPPER($1, 1) LOOP
        $2 := $2 || coleoptera.find_or_create_instruction($1[xIndex]);
      END LOOP;
    END;
  $BODY$;


-- as plruby, though I can't tell if I'm allowed to call the other DB function
-- this way, certainly I have no control over the path, so nfi
CREATE OR REPLACE
  FUNCTION coleoptera.find_or_create_instructions(instructions TEXT[])
  RETURNS coleoptera.instructions[]
  LANGUAGE PLRUBY VOLATILE
  AS $BODY$
    return if instructions.empty?
    instructions.collect { |elem| find_or_create_instruction(elem) }
  $BODY$;