hindley-milner

What are the limits of type inference? Which type systems have no general inference algorithm? Joe Wells showed that type inference is undecidable for System F, which is the most basic polymorphic lambda calculus, independently discovered by Girard and Reynolds. This is the most important result showing the limits of type inference. Here's an important problem that is still open: what is the best way to integrate Generalized Algebraic Data Types into Hindley-Milner type inference? Every year Simon Peyton Jones comes up with a new answers, which is supposedly better than the previous year's

I'm looking for information about the well-known Damas-Hindley-Milner algorithm to do type inference for functional languages, especially information about implementation. I already know how to do the Algorithm W , but I heard about recent new algorithms based on constraint generator/solver rather than usual unification. However, I can't manage to find any discussions about the implementation of those new algorithm. Any idea where I could find some partial information on ML inference ? If you're comfortable with ML code, the best way to find these things is to simply look into the

I am exposing a function which takes two parameters, one is a minimum bound and the other is a maximum bound. How can I ensure, using types, that for example the minimum bound is not greater than the maximum bound? I want to avoid creating a smart constructor and returning a Maybe because it would make the whole usage more cumbersome. Thank you This doesn't exactly answer your question, but one approach that sometimes works is to change your interpretation of your type. For example, instead of data Range = {lo :: Integer, hi :: Integer} you could use data Range = {lo :: Integer, size ::

Reading Disadvantages of Scala type system versus Haskell? , I have to ask: what is it, specifically, that makes Haskell's type system more powerful than other languages' type systems (C, C++, Java). Apparently, even Scala can't perform some of the same powers as Haskell's type system. What is it, specifically, that makes Haskell's type system (Hindley–Milner type inference) so powerful? Can you give an example? What is it, specifically, that makes Haskell's type system It has been engineered for the past decade to be both flexible -- as a logic for property verification -- and powerful.

I swear there used to be a T-shirt for sale featuring the immortal words: What part of do you not understand? In my case, the answer would be... all of it! In particular, I often see notation like this in Haskell papers, but I have no clue what any of it means. I have no idea what branch of mathematics it's supposed to be. I recognise the letters of the Greek alphabet of course, and symbols such as "∉" (which usually means that something is not an element of a set). On the other hand, I've never seen "⊢" before ( Wikipedia claims it might mean "partition" ). I'm also unfamiliar with the use of