There's also this obfuscated let f='.';o c(x:y)=x:c y;z c(x:y)=f:c y;p n='p':ap fix p(o.n)in f:f:p z defining the `bitmap' of prime numbers ..pp.p.p.

There's also this obfuscated let f='.';o c(x:y)=x:c y;z c(x:y)=f:c y;p n='p':ap fix p(o.n)in f:f:p z defining the `bitmap' of prime numbers ..pp.p.p...p.p...p.p...p.....p.p.....p...p.p...p.. ... while avoiding arithmetic altogether.