Euclidean distance

Euclidean distance of a vector in n dimensions
Usage:

echo( len3( [1,1,2] ) );
echo( len3( [1,1,2] - [0,2,0] ) );


function len3(v) =len(v)>1?

sqrt(addl([for(i=[0:len(v)-1])pow(v[i], 2)]))

:len(v)==1?v[0]:v; 
function addl(l,c=0)= len(l)-1 >c?l[c]+addl(l,c+1):l[c];