samer@4: % cpfields - Copy selected fields from one structure to another
samer@4: %
samer@4: % cpfields :: 
samer@4: %    C:{[N]->string}   ~'fields names to copy', 
samer@4: %    struct A          ~'struct with field names in A', 
samer@4: %    struct B          ~'struct with field names in B'
samer@4: % -> struct union(B,C) ~'struct with fields B union C' :-
samer@4: %  	subset(C,A)      ~'target fields must be in A'.
samer@4: function B=cpfields(fields,A,B)
samer@4: 	B=foldl(@(b,fn)setfield(b,fn,getfield(A,fn)),B,fields);
samer@4: