-bash-3.00$ createdb davinci;
CREATE DATABASE
-bash-3.00$ createlang plperl davinci;
-bash-3.00$ createlang plpgsql davinci;

Odd… no return code for createlang? Oh well… can’t be slowed down by that now!!
-bash-3.00$ psql -U postgres davinci
Welcome to psql 8.1.1, the PostgreSQL interactive terminal.
Type: copyright for distribution terms
h for help with SQL commands
? for help with psql commands
g or terminate with semicolon to execute query
q to quit
davinci=#

I then created Greg’s function “make_primes”…
davinci=#
davinci=# CREATE FUNCTION make_primes(INT)
davinci-# RETURNS SETOF INT
davinci-# LANGUAGE plperl IMMUTABLE AS
davinci-# $$
davinci$# (1 x $_) !~ /^1?$|^(11+?)+$/
davinci$# and return_next($_) for (1..shift);
davinci$# return;
davinci$# $$;
CREATE FUNCTION
davinci=#

And then went to install David’s “fib_fast” function… but whoops! His function doesn’t actually return a list of Fibonacci numbers, it returns a sum of them. No problem though, a few quick edits later and:
davinci=#
davinci=# CREATE OR REPLACE FUNCTION make_fibs(
davinci(# fib_for integer
davinci(# ) RETURNS setof integer AS $$
davinci$# DECLARE
davinci$# ret integer := 0;
davinci$# nxt integer := 1;
davinci$# tmp integer;
davinci$# BEGIN
davinci$# FOR num IN 1..fib_for LOOP
davinci$# tmp := ret;
davinci$# ret := nxt;
davinci$# nxt := tmp + nxt;
davinci$# IF nxt > fib_for THEN
davinci$# RETURN;
davinci$# ELSE
davinci$# RETURN NEXT nxt;
davinci$# END IF;
davinci$# END LOOP;
davinci$#
davinci$# RETURN;
davinci$# END;
davinci$# $$ LANGUAGE plpgsql;
CREATE FUNCTION
davinci=#

And now… the total mysteries of the universe were at my command:
davinci=# select * from make_fibs(50);
make_fibs
———–
1
2
3
5
8
13
21
34
(8 rows)
davinci=# select * from make_primes(50);
make_primes
————-
2
3
5
7
11
13
17
19
23
29
31
37
41
43
47
(15 rows)
davinci=# select * from make_fibs(50) intersect select * from make_primes(50);
make_fibs
———–
2
3
5
13
(4 rows)
davinci=# select * from make_fibs(100) intersect select * from make_primes(100);
make_fibs
———–
2
3
5
13
89
(5 rows)

Fascinating huh?