fix(enumerate): prioritize alphanumeric chars

Previously, `enumerate` would output characters in the "unicode order".
That means, characters which are early in the unicode range are output
first (such as "\u0000", "\u0001"). Now, the more common alphanumeric
characters are always produced first. That way, we get the more
representative strings tend to get enumerated first, which is useful
because we usually only look at the first few items in the enumeration.

Author: gruhn

src/char-set.ts

@@ -317,8 +317,28 @@ export function toString(set: CharSet): string {
 }
 
 export function enumerate(set: CharSet): Stream.Stream<string> {
+  // If we enumerate the set in "unicode order" then we only get
+  // chars like "\u0000", "\u0001" for a while. We prefer to enumerate
+  // more common characters first, since users will usually only 
+  // look at the first few items in the enumeration.
+  const lowerChars = charRange('a', 'z')
+  const upperChars = charRange('A', 'Z')
+  const numChars = charRange('0', '9')
+
+  // The input set minus the "common characters ranges":
+  const restChars = [lowerChars, upperChars, numChars].reduce(
+    (acc, item) => difference(acc, item), set
+  )
+
+  const rangesWithBiasedOrder = [
+    ...getRanges(intersection(lowerChars, set)),
+    ...getRanges(intersection(upperChars, set)),
+    ...getRanges(intersection(numChars, set)),
+    ...getRanges(restChars),
+  ]
+
   return Stream.concat(Stream.fromArray(
-    [...getRanges(set)].map(
+    rangesWithBiasedOrder.map(
       range => Stream.map(
         codePoint => String.fromCodePoint(codePoint),
         Stream.range(range.start, range.end)