You have declared a function that says that it can deal with any type `a` that the *caller* chooses, then provided an implementation that only supports Int.

Note that :: does not do conversion (as you said "Even though I am converting my 'value' parameter to Int"); it declares that the type of `value` *is* Int. Other types will be inferred to match, and this fails at `value:` in a context which wants the type to be a caller-specified `a`, not Int.
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