Source code in the egel programming language

import "prelude.eg"
import "io.ego"

using System
using List
using IO

def boardsize = 5

def empty = [ X Y -> 0 ]

def insert =
    [ X Y BOARD -> 
        [ X0 Y0 -> if and (X0 == X) (Y0 == Y) then 1
                    else BOARD X0 Y0 ] ]

def coords =
    let R = fromto 0 (boardsize - 1) in
        [ XX YY -> map (\X -> map (\Y -> X Y) YY) XX ] R R

def printcell =
    [ 0 -> print ". "
    | _ -> print "* " ]

def printboard =
    [ BOARD ->
        let M  = map [XX -> let _ = map [(X Y) -> printcell (BOARD X Y)] XX in print "\n" ] coords in
            nop ]

def count =
    [ BOARD, X, Y ->
        (BOARD (X - 1) (Y - 1)) + (BOARD (X) (Y - 1)) + (BOARD (X+1) (Y - 1)) +
        (BOARD (X - 1) Y) + (BOARD (X+1) Y) +
        (BOARD (X - 1) (Y+1)) + (BOARD (X) (Y+1)) + (BOARD (X+1) (Y+1)) ]

def next =
    [ 0 N -> if N == 3 then 1 else 0
    | _ N -> if or (N == 2) (N == 3) then 1 else 0 ]

def updateboard =
    [ BOARD ->
        let XX = map (\(X Y) -> X Y (BOARD X Y) (count BOARD X Y)) (flatten coords) in
        let YY = map (\(X Y C N) -> X Y (next C N)) XX in
            foldr [(X Y 0) BOARD -> BOARD | (X Y _) BOARD -> insert X Y BOARD ] empty YY ]

def blinker =
    (insert 1 2) @ (insert 2 2) @ (insert 3 2)

def main = 
    let GEN0 = blinker empty in
    let GEN1 = updateboard GEN0 in
    let GEN2 = updateboard GEN1 in
    let _ = map [ G -> let _ = print "generation:\n" in printboard G ] {GEN0, GEN1, GEN2} in
        nop