step
Type: step :: String -> String -> Pattern String
step acts as a kind of simple step-sequencer using strings. For example, step "sn" "x x 12 " is equivalent to the pattern of strings given by "sn ~ sn ~ sn:1 sn:2 ~". step substitutes the given string for each x, for each number it substitutes the string followed by a colon and the number, and for everything else it puts in a rest.
In other words, step generates a pattern of strings in exactly the syntax you'd want for selecting samples and that can be fed directly into the s function.
d1 $ s (step "sn" "x x 12 ")steps
Type: steps :: [(String,String)] -> Pattern String
steps is like step but it takes a list of pairs like step would and it plays them all simultaneously.
d1 $ s (steps [("cp","x x x x x x"),("bd", "xxxx")])step'
Type: step' :: [String] -> String -> Pattern String
step' is like step but more general, using the numbers in the step-sequencing string as indexes into the list of strings you give it.
d1 $ s (step' ["superpiano","supermandolin"] "0 1 000 1") # sustain 4 # n 0is equivalent to
d1 $ s "superpiano ~ supermandolin ~ superpiano!3 ~ supermandolin" # sustain 4 # n 0