At the basic level, there’s not much difference, but they’re still there. Haskell describes functions or values defined in a typeclass as ‘methods’, just as traits describe OOP methods in the objects they enclose. However, Haskell deals with these differently, treating them as individual values rather than pinning them to an object as OOP would … Read more
“Integer” is an arbitrary precision type: it will hold any number no matter how big, up to the limit of your machine’s memory…. This means you never have arithmetic overflows. On the other hand it also means your arithmetic is relatively slow. Lisp users may recognise the “bignum” type here. “Int” is the more common … Read more
Before I answer the main question, I’m going to try to define a bit more precisely what it would mean to write code in Haskell or Idris and compile it to run on an Ethereum-like blockchain. Idris is probably a better fit for this, but I’m going to use Haskell because that’s what I’m familiar … Read more
Here is how I pronounce them: >>= bind >> then *> then -> to a -> b: a to b <- bind (as it desugars to >>=) <$> (f)map <$ map-replace by 0 <$ f: “f map-replace by 0″ <*> ap(ply) (as it is the same as Control.Monad.ap) $ (none, just as ” ” [whitespace]) … Read more
I don’t see any published version of syntactic whose signature for sugarSym uses those exact type names, so I’ll be using the development branch at commit 8cfd02^, the last version which still used those names. So, why does GHC complain about the fi in your type signature but not the one for sugarSym? The documentation … Read more
Great question! There are several key differences. Representation A newtype guarantees that your data will have exactly the same representation at runtime, as the type that you wrap. While data declares a brand new data structure at runtime. So the key point here is that the construct for the newtype is guaranteed to be erased … Read more
A type constructor which is not a Functor: newtype T a = T (a -> Int) You can make a contravariant functor out of it, but not a (covariant) functor. Try writing fmap and you’ll fail. Note that the contravariant functor version is reversed: fmap :: Functor f => (a -> b) -> f a … Read more
Full disclosure: I’m one of the lead developers of Snap. First of all, let’s talk about what Snap is. Right now the Snap team maintains five different projects on hackage: snap-core, snap-server, heist, snap, and xmlhtml. snap-server is a web server that exposes the API defined by snap-core. heist is a templating system. xmlhtml is … Read more
Lists Rock By far the most friendly data structure for sequential data in Haskell is the List data [a] = a:[a] | [] Lists give you ϴ(1) cons and pattern matching. The standard library, and for that matter the prelude, is full of useful list functions that should litter your code (foldr,map,filter). Lists are persistant … Read more
It is not implemented because nobody requested it. The odd thing is that TH uses its own AST, which doesn’t follow internal compiler’s AST. As a result, any new feature (e.g. associated type families) is not automatically available via TH. Some one have to open a ticket and implement it. For the reference: internal reifyClass … Read more