perl -MUnicode::UCD=prop_invlist -MString::Range::Expand=expand_expr -MList::Util=pairmap -E 'say join(",", sort map {chr} expand_expr(join(",", pairmap{"[$a-".($b-1)."]"} prop_invlist("PosixAlpha"))))'
A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z