egison-4.1.0: sample/demo1.egi

-- Extract all twin primes from the infinite list of prime numbers with pattern matching!
def twinPrimes :=
  matchAll primes as list integer with
    | _ ++ $p :: #(p + 2) :: _ -> (p, p + 2)

-- Enumerate first 10 twin primes.
take 10 twinPrimes
-- => [(3, 5), (5, 7), (11, 13), (17, 19), (29, 31), (41, 43), (59, 61), (71, 73), (101, 103), (107, 109)]