Design a musical composition incorporating the alphabetic expression of the chosen structure and the provided melodic theme.
X:1
L:1/8
M:7/8
K:Amin
['EAc eA eA', 'EAc BA BA', 'ecA cA cA']  
X:1
L:1/8
M:7/8
K:Amin
|: EAc eA eA | EAc dA dA | EAc eA eA | dcd ef de | EAc eA eA | EAc dA dA | edc de fg | ecB A2 A2 :: 
 EAc BA BA | cBc de dA | EAc BA BA | cBA _BA GA | EAc BA BA | cBc dB cd | edc de fg | ecA A2 A2 :: 
 ecA cA cA | dBG Bc df | ecA cA cA | def de fg | ecA cA cA | dBG Bc df | edc de fg | ecA A2 A2 :|  