Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
M:2/2
K:D
['A F3']  
X:1
L:1/8
M:2/2
K:D
|: A3 B ADFA | dBBA G3 B | A F3 ABdf | edBA BcdB | A F3 ADFA | dBBA G3 B | A F3 ABdf |1 
 edBA BcdB :|  