diff --git a/Music/LilyPond/Light.hs b/Music/LilyPond/Light.hs
--- a/Music/LilyPond/Light.hs
+++ b/Music/LilyPond/Light.hs
@@ -1,71 +1,63 @@
 module Music.LilyPond.Light (module Music.LilyPond.Light
-                            ,module Music.LilyPond.Light.Constant
-                            ,module Music.LilyPond.Light.Constant.NoteName
-                            ,module Music.LilyPond.Light.Model
-                            ,module Music.LilyPond.Light.Output.LilyPond
-                            ,module Music.Theory.Duration
-                            ,module Music.Theory.Duration.Name
-                            ,module Music.Theory.Key
-                            ,module Music.Theory.Pitch) where
+                            ,module L) where
 
 import Data.List
 import Data.Monoid
 import Data.Ratio
-import Music.LilyPond.Light.Constant
-import Music.LilyPond.Light.Constant.NoteName
-import Music.LilyPond.Light.Model
-import Music.LilyPond.Light.Output.LilyPond
-import Music.Theory.Duration
-import Music.Theory.Duration.Name
-import Music.Theory.Pitch
-import Music.Theory.Key
+import Music.LilyPond.Light.Constant as L
+import Music.LilyPond.Light.Constant.NoteName as L
+import Music.LilyPond.Light.Model as L
+import Music.LilyPond.Light.Output.LilyPond as L
+import Music.Theory.Duration as L
+import Music.Theory.Duration.Name as L
+import Music.Theory.Key as L
+import Music.Theory.Pitch as L
+import Music.Theory.Pitch.Spelling
 
 -- * Music category predicates
 
+is_music_c :: Music_C -> Music -> Bool
+is_music_c c = (==) c . music_c
+
 is_note :: Music -> Bool
-is_note (Note _ _ _) = True
-is_note _ = False
+is_note = is_music_c Note_C
 
 is_chord :: Music -> Bool
-is_chord (Chord _ _ _) = True
-is_chord _ = False
+is_chord = is_music_c Chord_C
 
 is_rest :: Music -> Bool
-is_rest (Rest _ _) = True
-is_rest _ = False
+is_rest = is_music_c Rest_C
 
 is_mm_rest :: Music -> Bool
-is_mm_rest (MMRest _ _ _) = True
-is_mm_rest _ = False
+is_mm_rest = is_music_c MMRest_C
 
 is_grace :: Music -> Bool
-is_grace (Grace _) = True
-is_grace _ = False
+is_grace = is_music_c Grace_C
 
 is_after_grace :: Music -> Bool
-is_after_grace (AfterGrace _ _) = True
-is_after_grace _ = False
+is_after_grace = is_music_c AfterGrace_C
 
 -- | These are required to avoid issues in lilypond (see manual)
 is_grace_skip :: Music -> Bool
-is_grace_skip (Grace (Skip _)) = True
-is_grace_skip _ = False
+is_grace_skip m =
+    case m of
+      Grace (Skip _) -> True
+      _ -> False
 
 is_clef :: Music -> Bool
-is_clef (Clef _ _) = True
-is_clef _ = False
+is_clef = is_music_c Clef_C
 
 is_time :: Music -> Bool
-is_time (Time _) = True
-is_time _ = False
+is_time = is_music_c Time_C
 
 is_tempo :: Music -> Bool
-is_tempo (Tempo _ _) = True
-is_tempo _ = False
+is_tempo = is_music_c Tempo_C
 
 is_barlinecheck :: Music -> Bool
-is_barlinecheck (Command BarlineCheck) = True
-is_barlinecheck _ = False
+is_barlinecheck m =
+    case m of
+      Command BarlineCheck -> True
+      _ -> False
 
 is_tied :: Music -> Bool
 is_tied m =
@@ -75,8 +67,7 @@
       _ -> False
 
 is_tuplet :: Music -> Bool
-is_tuplet (Tuplet _ _ _) = True
-is_tuplet _ = False
+is_tuplet = is_music_c Tuplet_C
 
 -- * Pitch
 
@@ -98,7 +89,7 @@
          _ -> error ("clr_acc at non-note/chord: " ++ ly_music_elem m)
 
 octpc_to_note :: (Octave, PitchClass) -> Music
-octpc_to_note x = Note (octpc_to_pitch x) Nothing []
+octpc_to_note x = Note (octpc_to_pitch pc_spell_ks x) Nothing []
 
 -- * Rests
 
@@ -106,6 +97,7 @@
 r :: Duration -> Music
 r x = Rest x []
 
+-- | Multi-measure variant of 'r'.
 r' :: TimeSignature -> Music
 r' x = MMRest 1 x []
 
@@ -113,17 +105,17 @@
 empty_measure :: Integer -> Integer -> Music
 empty_measure n d = mconcat [MMRest 1 (n,d) [], l]
 
--- | Like empty_measure, but with an invisible rest.
+-- | Like 'empty_measure', but with an invisible rest.
 null_measure :: Integer -> Integer -> Music
 null_measure n d =
     let x = Duration d 0 1
     in mconcat (map Skip (genericReplicate n x) ++ [l])
 
--- | Like empty_measure but write time signature.
+-- | Like 'empty_measure' but write time signature.
 measure_rest :: Integer -> Integer -> Music
 measure_rest n d = mconcat [time_signature (n,d), empty_measure n d]
 
--- | Like measure_rest but write time signature.
+-- | Like 'measure_rest' but write time signature.
 measure_null :: Integer -> Integer -> Music
 measure_null n d = mconcat [time_signature (n,d), null_measure n d]
 
@@ -151,6 +143,9 @@
       [x] -> [m_annotate' as x]
       (x:xs') -> x : m_annotate_last' as xs'
 
+m_append :: [Music] -> Measure -> Measure
+m_append c (Measure as xs) = Measure as (xs++c)
+
 m_elements :: Measure -> [Music]
 m_elements (Measure as xs) = as ++ xs
 
@@ -159,7 +154,7 @@
 
 -- * Tuplets
 
--- | Apply fn to the duration of x, if it has a duration.
+-- | Apply a 'Duration' function to a 'Music' node, if it has a duration.
 edit_dur :: (Duration -> Duration) -> Music -> Music
 edit_dur fn x =
     case x of
@@ -228,7 +223,8 @@
       (6,2) -> [dotted_breve]
       _ -> error ("ts_whole_note: " ++ show t)
 
--- | Command to request that 4/4 and 2/2 etc. are typeset as fractions.
+-- | Command to request that @4\/4@ and @2\/2@ etc. are typeset as
+-- fractions.
 ts_use_fractions :: Music
 ts_use_fractions =
     let x = "\\override Staff.TimeSignature #'style = #'()"
@@ -264,7 +260,7 @@
 
 -- * Annotations
 
--- | Can a music element be annotated?
+-- | Can a 'Music' element be annotated?
 allows_annotations :: Music -> Bool
 allows_annotations m =
     is_note m ||
@@ -272,7 +268,7 @@
     is_rest m ||
     is_mm_rest m
 
--- | Add an annotation to music element.
+-- | Attempt to add an 'Annotation' to a 'Music' element.
 add_annotation :: Annotation -> Music -> Maybe Music
 add_annotation a m =
     case m of
@@ -282,22 +278,22 @@
       MMRest i j as -> Just (MMRest i j (as ++ [a]))
       _ -> Nothing
 
--- | Add an annotation to music element or error.
+-- | Add an 'Annotation' to a 'Music' element or 'error'.
 add_annotation_err :: Annotation -> Music -> Music
 add_annotation_err a m =
     case add_annotation a m of
       Just m' -> m'
       Nothing -> error ("add_annotation failed: " ++ show (a,ly_music_elem m))
 
--- | Add an annotation to music element, or error.
+-- | Infix form of 'add_annotation_err'.
 (&) :: Music -> Annotation -> Music
 m & a = add_annotation_err a m
 
--- | Add an annotation to a pitch.
+-- | Add an 'Annotation' to a 'Pitch'.
 (&#) :: Pitch -> Annotation -> Music
 x &# y = Note x Nothing [y]
 
--- | Add an annotation to music element.
+-- | Add an 'Annotation' to a 'Music' element.
 perhaps_annotate :: Annotation -> Music -> Music
 perhaps_annotate a m = maybe m id (add_annotation a m)
 
@@ -357,7 +353,7 @@
 place_above x = CompositeAnnotation [Above, x]
 place_below x = CompositeAnnotation [Below, x]
 
--- | Add an annotation to a note element, else identity.
+-- | Add an 'Annotation' to a @Note@ 'Music' element, else identity.
 note_annotate :: Annotation -> Music -> Music
 note_annotate a m =
     case m of
@@ -420,7 +416,10 @@
 p_or p1 p2 = \x -> p1 x || p2 x
 p_and p1 p2 = \x -> p1 x && p2 x
 
---  span_r (< 0) [-1,-2,1,2,3,-3,-4] => ([-1,-2],[1,2,3],[-3,-4])
+-- | Variant of 'span' that further spans the reverse of the right
+-- hand side.
+--
+--  > span_r (< 0) [-1,-2,1,2,3,-3,-4] == ([-1,-2],[1,2,3],[-3,-4])
 span_r :: (a -> Bool) -> [a] -> ([a], [a], [a])
 span_r fn xs =
     let (o1,o2) = span fn xs
@@ -451,11 +450,11 @@
 
 -- * Duration
 
--- | Add duration to pitch to make a note.
+-- | Add 'Duration' to 'Pitch' to make a @Note@ 'Music' element.
 (##) :: Pitch -> Duration -> Music
 x ## d = Note x (Just d) []
 
--- | Add duration to pitch to make a note.
+-- | Add 'Duration' to either a @Note@ or @Chord@ 'Music' element.
 (#) :: Music -> Duration -> Music
 x # d =
     case x of
@@ -483,7 +482,7 @@
 
 -- * Commands
 
--- | Construct bar number check.
+-- | Construct bar number check command.
 bar_number_check :: Integer -> Music
 bar_number_check = Command . BarNumberCheck
 
@@ -495,6 +494,7 @@
 partial :: Duration -> Music
 partial = Command . Partial
 
+-- | Set or unset the @circled-tip@ hairpin attribute.
 hairpin_circled_tip :: Bool -> Music
 hairpin_circled_tip x =
     let c = if x
@@ -502,6 +502,7 @@
             else "\\revert Hairpin #'circled-tip"
     in Command (User c)
 
+-- | Set or unset the @to-barline@ hairpin attribute.
 hairpin_to_barline :: Bool -> Music
 hairpin_to_barline x =
     let c = if x
@@ -602,7 +603,7 @@
 tremolo = Tremolo
 
 -- | Interior polyphony.  For two part music on one staff see
---   two_part_staff.
+--   'two_part_staff'.
 polyphony :: Music -> Music -> Music
 polyphony = Polyphony
 
diff --git a/Music/LilyPond/Light/Analysis.hs b/Music/LilyPond/Light/Analysis.hs
--- a/Music/LilyPond/Light/Analysis.hs
+++ b/Music/LilyPond/Light/Analysis.hs
@@ -1,5 +1,6 @@
 module Music.LilyPond.Light.Analysis where
 
+import Control.Arrow
 import Data.Function
 import Data.List
 import Data.Maybe
@@ -9,7 +10,7 @@
 import Music.LilyPond.Light.Model
 import Music.Theory.Duration
 import Music.Theory.Pitch
-import qualified Music.Theory.Spelling as T
+import qualified Music.Theory.Pitch.Spelling as T
 
 type R = Double
 
@@ -192,7 +193,7 @@
 -- | Update state part number.
 st_set_part :: Locate_ST -> Part_ID -> Locate_ST
 st_set_part st v =
-    let (ts, (Location b p _ m)) = st
+    let (ts, Location b p _ m) = st
     in (ts, Location b p v m)
 
 -- | Update state part number.
@@ -253,7 +254,7 @@
                   st' = map (st_set_part st) [v ..]
                   r = zipWith locate_st st' [x0,x1]
                   ((st'',_):_) = r
-              in (st'', this : concat (map snd r))
+              in (st'', this : concatMap snd r)
          Empty -> (st, [this]) -- error "locate_st: empty"
 
 -- | Run location calculations.
@@ -286,7 +287,7 @@
 lm_pitches :: [LM] -> [Pitch]
 lm_pitches l =
     let m = map snd l
-        p = concat (map collect_pitches (filter has_pitch m))
+        p = concatMap collect_pitches (filter has_pitch m)
     in (nub . sort) p
 
 lm_pcset :: [LM] -> [PitchClass]
@@ -354,7 +355,7 @@
 lv_last_measure :: [LV a] -> Measure
 lv_last_measure =
     let fn = compare `on` measure
-    in measure . head . reverse . sortBy fn . map fst
+    in measure . last . sortBy fn . map fst
 
 time_unpack :: Music -> TimeSignature
 time_unpack (Time t) = t
@@ -369,8 +370,8 @@
         ps = lv_group_parts ts'
         e xs = let (l,t) = last xs
                in (t, lv_last_measure m' - measure l)
-        f ((l1, t1), (l2, _)) = (t1, measure_diff l1 l2)
-    in map (\ys -> map f (zip ys (tail ys)) ++ [e ys]) ps
+        f (l1, t1) (l2, _) = (t1, measure_diff l1 l2)
+    in map (\ys -> zipWith f ys (tail ys) ++ [e ys]) ps
 
 ts_structure' :: [Music] -> [[(TimeSignature, Integer)]]
 ts_structure' = ts_structure . mconcat
@@ -388,7 +389,7 @@
 lm_ts_map :: [LM] -> TimeSignature_Map
 lm_ts_map xs =
     let xs' = filter (L.is_time . snd) xs
-    in map (\(t,x) -> (measure t, time_unpack x)) xs'
+    in map (measure *** time_unpack) xs'
 
 ts_map :: [Music] -> TimeSignature_Map
 ts_map = lm_ts_map . locate'
@@ -411,9 +412,11 @@
 -- * Tempo
 
 lm_tempo_map :: [LM] -> [(Measure,(Duration,Integer))]
-lm_tempo_map xs =
-    let xs' = filter (L.is_tempo . snd) xs
-    in map (\(t,Tempo d x) -> (measure t, (d,x))) xs'
+lm_tempo_map =
+    let f (t,i) = case i of
+                    Tempo d x -> Just (measure t,(d,x))
+                    _ -> Nothing
+    in mapMaybe f
 
 tempo_map :: [Music] -> [(Measure,(Duration,Integer))]
 tempo_map = lm_tempo_map . locate'
@@ -444,7 +447,7 @@
 
 -- | Apply functions to keys and values.
 kv_map :: (k -> k') -> (v -> v') -> [(k,v)] -> [(k',v')]
-kv_map f g = map (\(k,v) -> (f k, g v))
+kv_map f g = map (f *** g)
 
 -- * Measure collation
 
@@ -603,7 +606,7 @@
 
 -- * Validation
 
-v_assert :: String -> (Music -> Bool) -> (Music -> Maybe String)
+v_assert :: String -> (Music -> Bool) -> Music -> Maybe String
 v_assert str fn m =
     if fn m then Nothing else Just str
 
diff --git a/Music/LilyPond/Light/Constant.hs b/Music/LilyPond/Light/Constant.hs
--- a/Music/LilyPond/Light/Constant.hs
+++ b/Music/LilyPond/Light/Constant.hs
@@ -173,7 +173,7 @@
 paper_incr_size x =
     let wd = paper_width x
         ht = paper_height x
-    in x { paper_width = ht, paper_height = (length_scale 2 wd) }
+    in x {paper_width = ht, paper_height = length_scale 2 wd}
 
 a3_paper :: Paper
 a3_paper = paper_incr_size a4_paper
@@ -185,13 +185,13 @@
 landscape x =
     let wd = paper_width x
         ht = paper_height x
-    in x { paper_width = ht, paper_height = wd }
+    in x {paper_width = ht, paper_height = wd}
 
 -- * Settings
 
 default_score_settings :: Score_Settings
 default_score_settings =
-    Score_Settings { independent_time_signatures = False }
+    Score_Settings {independent_time_signatures = False}
 
 -- * Header
 
diff --git a/Music/LilyPond/Light/Model.hs b/Music/LilyPond/Light/Model.hs
--- a/Music/LilyPond/Light/Model.hs
+++ b/Music/LilyPond/Light/Model.hs
@@ -133,8 +133,49 @@
                  | Scale_Durations
                    deriving (Eq, Show)
 
+-- | 'Music' element category enumeration.
+data Music_C = Note_C
+             | Chord_C
+             | Tremolo_C
+             | Rest_C | MMRest_C | Skip_C
+             | Repeat_C
+             | Tuplet_C
+             | Grace_C | AfterGrace_C
+             | Join_C
+             | Clef_C
+             | Time_C
+             | Key_C
+             | Tempo_C
+             | Command_C
+             | Polyphony_C
+             | Empty_C
+               deriving (Eq,Enum,Bounded)
+
+-- | Categorise 'Music' element.
+music_c :: Music -> Music_C
+music_c m =
+    case m of
+      Note _ _ _ -> Note_C
+      Chord _ _ _ -> Chord_C
+      Tremolo _ _ -> Tremolo_C
+      Rest _ _ -> Rest_C
+      MMRest _ _ _ -> MMRest_C
+      Skip _ -> Skip_C
+      Repeat _ _ -> Repeat_C
+      Tuplet _ _ _ -> Tuplet_C
+      Grace _ -> Grace_C
+      AfterGrace _ _ -> AfterGrace_C
+      Join _ -> Join_C
+      Clef _ _ -> Clef_C
+      Time _ -> Time_C
+      Key _ _ _ -> Key_C
+      Tempo _ _ -> Tempo_C
+      Command _ -> Command_C
+      Polyphony _ _ -> Polyphony_C
+      Empty -> Empty_C
+
 data Music = Note { note_pitch :: Pitch
-                  , note_duration :: (Maybe Duration)
+                  , note_duration :: Maybe Duration
                   , note_annotations :: [Annotation] }
            | Chord { chord_notes :: [Music]
                    , chord_duration :: Duration
@@ -160,7 +201,7 @@
 instance Monoid Music where
     mempty = Empty
     mappend x y = Join [x,y]
-    mconcat xs = Join xs
+    mconcat = Join
 
 type Staff_Name = (String,String)
 
diff --git a/Music/LilyPond/Light/Output/LilyPond.hs b/Music/LilyPond/Light/Output/LilyPond.hs
--- a/Music/LilyPond/Light/Output/LilyPond.hs
+++ b/Music/LilyPond/Light/Output/LilyPond.hs
@@ -1,7 +1,6 @@
 module Music.LilyPond.Light.Output.LilyPond (ly_work
                                             ,ly_music_elem) where
 
-import Data.List
 import Music.LilyPond.Light.Model
 import Music.Theory.Pitch
 import Music.Theory.Duration
@@ -163,7 +162,7 @@
       Open -> "\\open"
       Portato -> "\\portato"
       Staccato -> "\\staccato"
-      StemTremolo x -> ":" ++ show x
+      StemTremolo x -> ':' : show x
       Stopped -> "\\stopped"
       Tenuto -> "\\tenuto"
       Trill -> "\\trill"
@@ -221,7 +220,7 @@
       Above -> "^"
       Below -> "_"
       Text x -> ly_str x
-      CompositeAnnotation xs -> intercalate " " (map ly_annotation xs)
+      CompositeAnnotation xs -> unwords (map ly_annotation xs)
       ReminderAccidental -> "" -- see ly_pitch
       CautionaryAccidental -> "" -- see ly_pitch
 
@@ -386,7 +385,7 @@
 
 ly_layout :: Score_Settings -> [String]
 ly_layout x =
-    let mk_i nm = printf "\\context { \\%s \\consists \"Instrument_name_engraver\"}" nm
+    let mk_i = printf "\\context { \\%s \\consists \"Instrument_name_engraver\"}"
         is = unlines (map mk_i ["StaffGroup","ChoirStaff","GrandStaff"])
     in ["\\layout", "{"
        ,if independent_time_signatures x
@@ -407,7 +406,7 @@
              ly_paper p ++
              ly_header hdr ++
              ly_score sc
-    in concat (intersperse " " xs)
+    in unwords xs
 
 ly_music_elem :: Music -> String
-ly_music_elem = concat . intersperse " " . ly_music
+ly_music_elem = unwords . ly_music
diff --git a/hly.cabal b/hly.cabal
--- a/hly.cabal
+++ b/hly.cabal
@@ -1,5 +1,5 @@
 Name:              hly
-Version:           0.1
+Version:           0.11
 Synopsis:          Haskell LilyPond
 Description:       A very lightweight embedding of the lilypond
                    typesetting model in haskell
@@ -10,14 +10,14 @@
 Maintainer:        rd@slavepianos.org
 Stability:         Experimental
 Homepage:          http://slavepianos.org/rd/?t=hly
-Tested-With:       GHC == 6.12.1
+Tested-With:       GHC == 7.2.2
 Build-Type:        Simple
-Cabal-Version:     >= 1.6
+Cabal-Version:     >= 1.8
 Data-Files:        README
 
 Library
-  Build-Depends:   base == 4.*,
-                   hmt
+  Build-Depends:   base==4.*,
+                   hmt==0.11.*
   GHC-Options:     -Wall -fwarn-tabs
   Exposed-modules: Music.LilyPond.Light
                    Music.LilyPond.Light.Analysis