Data commit

Task/Align-columns/Standard-ML/align-columns.ml

@@ -0,0 +1,29 @@
+fun curry f x y = f (x, y)
+fun uncurry f (x, y) = f x y
+
+fun maxWidths ([], widths) = widths
+  | maxWidths (strings, []) = map size strings
+  | maxWidths (s :: ss, w :: ws) = Int.max (size s, w) :: maxWidths (ss, ws)
+
+val alignL = uncurry (StringCvt.padRight #" ")
+and alignR = uncurry (StringCvt.padLeft #" ")
+
+fun alignC (w, s) =
+  alignL (w, alignR ((w + size s) div 2, s))
+
+fun formatTable tab =
+  let
+    val columnWidths = foldl maxWidths [] tab
+  in
+    fn f => String.concatWith "\n"
+      (map (String.concatWith " " o curry (ListPair.map f) columnWidths) tab)
+  end
+
+val readTable =
+  map (String.fields (curry op= #"$"))
+  o String.tokens (curry op= #"\n")
+  o TextIO.inputAll
+
+(* test stdin with all alignments *)
+val () = print (String.concatWith "\n\n"
+  (map (formatTable (readTable TextIO.stdIn)) [alignL, alignC, alignR]) ^ "\n")