// Ackermann function

`export ack : ([I64; I64.m; I64.n]
    ? {
        |(m < 0; n < 0) { 0 }
        m = 0 { n + 1 }
        &(m > 0; n = 0) { ack `sync (m - 1; 1) }
        { ack `sync (m - 1; ack `sync (m; n - 1)) }
    }
)

`export ack_string : ([String; I64.m; I64.n]
    "#MAGENTA#ack#(#CYAN#%#, #CYAN#%#) #WHITE#=# #GREEN#%#\n" `format (m; n; ack `sync (m; n))
)

`is_main ([Void]
    `use "sys" [args]
    ? 4 != `length args {
         `return `error String $ (
            "#BOLD#RED#Got: %#\n" `format " " `join args
            "#BOLD#WHITE#Usage: % % <m> <n>#\n" `format (args `get 0; args `get 1)
         )
    }
    `value ack_string `sync (I64 $ args `get -2; I64 $ args `get -1)
)