1 files changed, 98 insertions, 0 deletions
diff --git a/lux-r/source/luxc/lang/synthesis/variable.lux b/lux-r/source/luxc/lang/synthesis/variable.lux
new file mode 100644
index 000000000..f6a45b02e
--- /dev/null
+++ b/lux-r/source/luxc/lang/synthesis/variable.lux
@@ -0,0 +1,98 @@
+(.module:
+  lux
+  (lux (data [number]
+             (coll [list "list/" Fold<List> Monoid<List>]
+                   ["s" set])))
+  (luxc (lang ["la" analysis]
+              ["ls" synthesis]
+              [".L" variable #+ Variable])))
+
+(def: (bound-vars path)
+  (-> ls.Path (List Variable))
+  (case path
+    (#ls.BindP register)
+    (list (.int register))
+
+    (^or (#ls.SeqP pre post) (#ls.AltP pre post))
+    (list/compose (bound-vars pre) (bound-vars post))
+    
+    _
+    (list)))
+
+(def: (path-bodies path)
+  (-> ls.Path (List ls.Synthesis))
+  (case path
+    (#ls.ExecP body)
+    (list body)
+
+    (#ls.SeqP pre post)
+    (path-bodies post)
+
+    (#ls.AltP pre post)
+    (list/compose (path-bodies pre) (path-bodies post))
+    
+    _
+    (list)))
+
+(def: (non-arg? arity var)
+  (-> ls.Arity Variable Bit)
+  (and (variableL.local? var)
+       (n/> arity (.nat var))))
+
+(type: Tracker (s.Set Variable))
+
+(def: init-tracker Tracker (s.new number.Hash<Int>))
+
+(def: (unused-vars current-arity bound exprS)
+  (-> ls.Arity (List Variable) ls.Synthesis (List Variable))
+  (let [tracker (loop [exprS exprS
+                       tracker (list/fold s.add init-tracker bound)]
+                  (case exprS
+                    (#ls.Variable var)
+                    (if (non-arg? current-arity var)
+                      (s.remove var tracker)
+                      tracker)
+                    
+                    (#ls.Variant tag last? memberS)
+                    (recur memberS tracker)
+
+                    (#ls.Tuple membersS)
+                    (list/fold recur tracker membersS)
+
+                    (#ls.Call funcS argsS)
+                    (list/fold recur (recur funcS tracker) argsS)
+                    
+                    (^or (#ls.Recur argsS)
+                         (#ls.Procedure name argsS))
+                    (list/fold recur tracker argsS)
+
+                    (#ls.Let offset inputS outputS)
+                    (|> tracker (recur inputS) (recur outputS))
+
+                    (#ls.If testS thenS elseS)
+                    (|> tracker (recur testS) (recur thenS) (recur elseS))
+
+                    (#ls.Loop offset initsS bodyS)
+                    (recur bodyS (list/fold recur tracker initsS))
+
+                    (#ls.Case inputS outputPS)
+                    (let [tracker' (list/fold s.add
+                                              (recur inputS tracker)
+                                              (bound-vars outputPS))]
+                      (list/fold recur tracker' (path-bodies outputPS)))
+
+                    (#ls.Function arity env bodyS)
+                    (list/fold s.remove tracker env)
+
+                    _
+                    tracker
+                    ))]
+    (s.to-list tracker)))
+
+## (def: (optimize-register-use current-arity [pathS bodyS])
+##   (-> ls.Arity [ls.Path ls.Synthesis] [ls.Path ls.Synthesis])
+##   (let [bound (bound-vars pathS)
+##         unused (unused-vars current-arity bound bodyS)
+##         adjusted (adjust-vars unused bound)]
+##     [(|> pathS (clean-pattern adjusted) simplify-pattern)
+##      (clean-expression adjusted bodyS)]))