Hy version kind of works

livesort_hy/__init__.py

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+import hy
+from livesort_hy.livesort import Livesort
+# This allows `unittest.main` to discover these tests
+from livesort_hy.test_livesort import TestLivesort

livesort_hy/livesort.hy

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+(import [bisect [bisect]])
+
+(defclass Livesort []
+  (defn __init__ [self
+                  next-line ; iterable function yielding lines of text
+                  print     ; function to write output
+                  height    ; window/screen height in lines
+                  width     ; window/screen width in characters
+                  ]
+    (setv self.next-line next-line
+          self.print print
+          self.height height
+          self.width width
+          self.lines (list)
+          self.screen (* height [None])))
+  (defn sortline [self line]
+    "Insort a line"
+    (when (line.strip)
+      ;; Normally would use `insort` but there's going to be more
+      (self.lines.insert (bisect self.lines line) line)))
+  (defn render [self]
+    "Produce a list of the lines which should be visible, cropped to `width`"
+    (list (map (fn [line] (cut line 0 self.width))
+               (cut self.lines 0 self.height))))
+  (defn display [self]
+    "Compare `(self.render)` to `self.screen` and return a string that
+will update the display."
+    (setv output (list)
+          lines (self.render)
+          changed? False)
+    (output.append "")    ; Home cursor
+    (for [lineno (range self.height)]
+      (setv line (if (< lineno (len lines)) (get lines lineno) ""))
+      (unless (= line (get self.screen lineno))
+        (setv (get self.screen lineno) line
+              changed? True)
+        ;; ^[[K to erase any characters that follow on this line
+        (.append output (.format "{}"
+                                 (.rstrip line (chr 0x0a)))))
+      (.append output (chr 0x0a))) ; Move to beginning of next line
+    ;; if something changed, don't bother outputting the last cursor
+    ;; movement code.  If nothing changed, don't bother outputting
+    ;; anything.
+    (if changed? (.join "" (cut output 0 -1)) ""))
+  (defn livesort [self]
+    "Process every input line, updating screen each line"
+    (for [line self.next-line]
+      (.sortline self line)
+      (.print self (.display self)))))
+
+(defmain
+  ()
+  (import sys os)
+  (.livesort
+    (Livesort sys.stdin
+              (fn [data] (sys.stdout.write data) (sys.stdout.flush))
+              (int (or (os.getenv "LINES") "24"))
+              (int (or (os.getenv "COLUMNS") "80")))))

livesort_hy/test_livesort.hy

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+(import [livesort_hy [Livesort]])
+(import unittest)
+
+
+(defclass TestLivesort [unittest.TestCase]
+  (defn setUp [self] 
+    (setv self.input-buf (list)
+          self.output-buf (list)
+          self.ls (Livesort self.input-buf self.output-buf.append 4 8)))
+
+  (defn tearDown [self]
+    (del self.ls
+         self.output-buf
+         self.input-buf))
+
+  (defn test_Livesort [self]
+    (self.assertEqual self.ls.next-line self.input-buf)
+    (self.assertEqual self.ls.print self.output-buf.append)
+    (self.assertEqual self.ls.height 4)
+    (self.assertEqual self.ls.width 8)
+    (self.assertFalse self.ls.lines)
+    (self.assertTrue self.ls.screen)
+    (for [line self.ls.screen]
+      (self.assertEqual None line)))
+
+  (defn test_sortline [self]
+    (self.assertFalse self.ls.lines)
+    (self.ls.sortline "line 2")
+    (self.assertEqual self.ls.lines ["line 2"])
+    (self.ls.sortline "line 1")
+    (self.assertEqual self.ls.lines ["line 1" "line 2"]))
+
+  (defn test_render [self]
+    (self.ls.sortline "line 1")
+    (self.assertEqual (self.ls.render)
+                      ["line 1"]))
+
+  (defn test_display [self]
+    ;; I got fed up trying to write this sensibly, will go away after refacor
+    (self.assertEqual "
+
+
+" (self.ls.display))
+    (self.ls.sortline "line 1")
+    (self.assertEqual "line 1
+
+
+" (self.ls.display)))
+
+  ;; note (unfortunate) capitalization
+  (defn test_livesort [self]
+    (self.input-buf.append "line 1")
+    (self.ls.livesort)))