countRepeats doesn't work as advertised

[rampion]

The docs for countRepeats say it should "[c]ount the number of times a sequence is repeated in the input sequence that was used to construct the suffix tree."

This works for some examples - the string "aba" should occur 4 times in "abab abac abad abaa"

λ SuffixTree.countRepeats "aba" $ SuffixTree.construct "abab abac abad abaa"
4

But not for others - the string "aba" should occur 4 times in "bababababab"

λ SuffixTree.countRepeats "aba" $ SuffixTree.construct "bababababab"
1

[xogcox]

This is likely related to issue #4. When constructing trees, it is necessary to terminate the input string with a character that does not occur at any other location in the string. Otherwise, the tree will not have the expected properties. Adding a $ character to the input string in the above example resolves the problem.

λ SuffixTree.countRepeats "aba" $ SuffixTree.construct "bababababab$"
4