Design a musical composition incorporating the alphabetic expression of the chosen structure and the provided melodic theme.
X:1
L:1/8
M:2/2
K:Gmin
['G>A B>c d2 G2 g2 ^f>g a2', 'G2 A B2 G>B c2 F>c B2']  
X:1
L:1/8
M:2/2
K:Gmin
 G>A B>c d2 G2 | g2 ^f>g a2 d2 | b2 a>g f>e d2 | c>d B>c A2 G2 |] A | B2 G>B c2 F>c | 
 B2 G>d c2 B2 | f2 f>e d>c B>B | c>d B>c A2 G2 |]  