Added a working link for Wadler’s How to replace failure by a list of…

… successes

typeclassopedia.md

@@ -280,7 +280,7 @@ Most of the standard types which are instances of `Functor` are also instances o
 
 `Maybe` can easily be made an instance of `Applicative`; writing such an instance is left as an exercise for the reader.
 
-The list type constructor `[]` can actually be made an instance of `Applicative` in two ways; essentially, it comes down to whether we want to think of lists as ordered collections of elements, or as contexts representing multiple results of a nondeterministic computation (see Wadler’s [How to replace failure by a list of successes](http://www.springerlink.com/content/y7450255v2670167/)).
+The list type constructor `[]` can actually be made an instance of `Applicative` in two ways; essentially, it comes down to whether we want to think of lists as ordered collections of elements, or as contexts representing multiple results of a nondeterministic computation (see Wadler’s [How to replace failure by a list of successes](https://rkrishnan.org/files/wadler-1985.pdf)).
 
 Let’s first consider the collection point of view.  Since there can only be one instance of a given type class for any particular type, one or both of the list instances of `Applicative` need to be defined for a `newtype` wrapper; as it happens, the nondeterministic computation instance is the default, and the collection instance is defined in terms of a `newtype` called `ZipList`. This instance is: