Modified code to accommodate 'Null' trees

This commit is contained in:
Tong-Kiat Tan 2014-08-10 09:20:00 +08:00
parent f810b17aff
commit 3500c3cfb2

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@ -21,3 +21,4 @@ valid (Node v l r) = leftValid && rightValid
where leftValid = if notNull l then valid l && value l <= v else True
rightValid = if notNull r then valid r && v <= value r else True
notNull t = t/=Null
valid Null = True