What is the Haskell-style type signature called (i.e., who is it named after)? A type signature in Haskell is written in the following format:

functionName :: arg1Type -&gt; arg2Type -&gt; returnType


There's a (hyphenated, after a person or persons) name for this style of type signature (which predates Haskell), but it's escaping me and I can't find it anywhere.
Is it Hindley-Milner type system by any chance?