To do this you need to replace copySocket with two different functions, one to handle data from the plain socket to SSL and the other from SSL to the plain socket: copyIn :: SSL.SSL -> Socket -> IO () copyIn src dst = go where go = do buf <- SSL.read src 4096 unless (B.null … Read more
You’re actually doing pretty well to have a 51ms pause time with over 200Mb of live data. The system I work on has a larger max pause time with half that amount of live data. Your assumption is correct, the major GC pause time is directly proportional to the amount of live data, and unfortunately … Read more
The phenomenon comes from the amount of shared beta-reduction steps, which can be dramatically different in Haskell-style lazy evaluation (or usual call-by-value, which is not that far in this respect) and in Vuillemin-Lévy-Lamping-Kathail-Asperti-Guerrini-(et al…) “optimal” evaluation. This is a general feature, that is completely independent from the arithmetic formulas you could use in this particular … Read more
In a data declaration, a type constructor is the thing on the left hand side of the equals sign. The data constructor(s) are the things on the right hand side of the equals sign. You use type constructors where a type is expected, and you use data constructors where a value is expected. Data constructors … Read more
Yes, there’s a nice way of updating record fields. In GHCi you can do — > data Foo = Foo { a :: Int, b :: Int, c :: String } — define a Foo > let foo = Foo { a = 1, b = 2, c = “Hello” } — create a Foo … Read more
I guess I can answer this from authority. Is there a reason for using the books way that is much better than using all ($) symbols? There’s no special reason. Bryan and I both prefer to reduce line noise. . is quieter than $. As a result, the book uses the f . g . … Read more
You can pass the argument to ghc from ghc-mod as: $ ghc-mod lint *.hs -g -dsuppress-module-prefixes This will send the argument -dsuppress-module-prefixes to ghc.
1: The problem in the example f :: State s a f = State $ \x -> y where y = … x … is the parameter x. Things in the where clause can refer only to the parameters of the function f (there are none) and things in outer scopes. 2: To use a … Read more
Esqueleto is NOT meant to handle list of sublists (multidimensional list) out of the box yet! Data.List.groupBy that ‘cdk’ advised to you can group only list itself, but not what you was asking for. For your case I would insistently advise you to use a classic SQL queries. You can run n+1 queries, but do … Read more
Don’t be scared! The reader monad is actually not so complicated, and has real easy-to-use utility. There are two ways of approaching a monad: we can ask What does the monad do? What operations is it equipped with? What is it good for? How is the monad implemented? From where does it arise? From the … Read more