Develop a musical composition by integrating the alphabetically represented musical pattern and the supplied melodic theme.
X:1
L:1/8
M:2/4
K:G
['A2 A2']  
X:1
L:1/8
M:2/4
K:G
 D | GABc | d2 Bd | c2 Ac | B2 BA | GABc | d2 Bd | cAFA | G2 z2 | A2 A2 | A2 AB | AGFE | DEFG | 
 A2 A2 | A2 AB | AGFE | D4 | d4 | G4 | d4 | G2 z |]  