Musical ciphers have been used by Western composers for centuries. They are a means of transforming text (usually a name) into a musical motif using logical relations between letters and pitches.
Since Western notation uses letters for pitch-names, the most obvious method is to map each letter onto its corresponding (or parallel) pitch. However, this only works for the letters A to G, as Western notation only uses the pitch-names A to G. As a result, composers have had to find workarounds to accommodate for other letters.
For example, in one piece, the Romantic-era composer Robert Schumann created a melody out of his wife Clara's name, transforming the letters into the musical pitches C(#)BAG(#)A. For the letters c and a, Schumann used the logical pitches C(#) and A. For the letters l and r, he simply assigned the pitches B and G(#), as they make melodic sense of the surrounding pitches.
Clarallel builds upon this method used by Schumann. In addition to the letters A to G, some other letters have default and logical corresponding pitches: k, x and q map onto C; and i and y map onto E. From this, the algorithm assigns the resulting letters to the pitches that will result in the most beautiful melody. Furthermore, all instances of a letter in a name will have the same corresponding pitch. For example, Clarallel converts the name Hannah to the pitches GABBAG. Here, h and n consistently map onto G and B respectively.
The short harmonised melodies that Clarallel generates can be used as the starting points for more complex compositions. For example, this is a short piece I wrote using the melody generated for the name Lewis Jones.