target="METHINKS IT IS LIKE A WEASEL";
fitness(s)=-dist(Vec(s),Vec(target));
dist(u,v)=sum(i=1,min(#u,#v),u[i]!=v[i])+abs(#u-#v);
letter()=my(r=random(27)); if(r==26, " ", Strchr(r+65));
insert(v,x=letter())=
{
	my(r=random(#v+1));
	if(r==0, return(concat([x],v)));
	if(r==#v, return(concat(v,[x])));
	concat(concat(v[1..r],[x]),v[r+1..#v]);
}
delete(v)=
{
	if(#v<2, return([]));
	my(r=random(#v)+1);
	if(r==1, return(v[2..#v]));
	if(r==#v, return(v[1..#v-1]));
	concat(v[1..r-1],v[r+1..#v]);
}
mutate(s,rateM,rateI,rateD)=
{
	my(v=Vec(s));
	if(random(1.)<rateI, v=insert(v));
	if(random(1.)<rateD, v=delete(v));
	for(i=1,#v,
		if(random(1.)<rateM, v[i]=letter())
	);
	concat(v);
}
evolve(C,rate)=
{
	my(parent=concat(vector(#target,i,letter())),ct=0);
	while(parent != target,
		print(parent" "fitness(parent));
		my(v=vector(C,i,mutate(parent,rate,0,0)),best,t);
		best=fitness(parent=v[1]);
		for(i=2,C,
			t=fitness(v[i]);
			if(t>best, best=t; parent=v[i])
		);
		ct++
	);
	print(parent" "fitness(parent));
	ct;
}
evolve(35,.05)