Construct a melodic piece using the designated alphabetic pattern and the provided musical theme.
X:1
L:1/8
M:6/8
K:D
['F2 A', 'a2 f']  
X:1
L:1/8
M:6/8
K:D
|: [AA,] | DED F2 A | d2 f ecA | G2 B F2 A | E2 F GFE | DED F2 A | d2 f ecA | Bgf edc | (d3 d2) :: 
 a | a2 f d2 f | A2 a agf | g2 e c2 e | A2 g gfe | f2 d g2 e | a2 f bag | fed edc | (d3 d2) :|  