Design a musical composition incorporating the alphabetic expression of the chosen structure and the provided melodic theme.
X:1
L:1/8
M:4/4
K:G
['B2 dB G3 B AD (3DDD dDcA', 'A B3 d gfed ^c3 e agfe', 'BcdB GABG', 'A BGBd gfed ^c3 e agfe fAaf']  
X:1
L:1/8
M:4/4
K:G
 B2 dB G3 B | AD (3DDD dDcA | BcdB GB B2 | ADFA G3 A :: B3 d gfed | ^c3 e agfe | f2 af df f2 | 
 fe^ce d3 f | gfed (3^cde a2- | agfe dcBA | B2 dB GB B2 | ADFA G3 A :| BcdB GABG | AD (3DDD dDcD | 
 BcdB GABG | ADFA G3 A :: BGBd gfed | ^c3 e agfe | fAaf defd | eA^ce d3 f | gfed (3efg a2- | 
 agfe dcBA | B2 dB GABG | ADFA G3 A :|  