The source code for Control.Parallel.Strategies ( http://hackage.haskell.org/packages/archive/parallel/3.1.0.1/doc/html/src/Control-Parallel-Strategies.html#Eval ) contains a type Eval defined as: ...

I have a piece of code that repeatedly samples from a probability distribution using sequence. Morally, it does something like this: sampleMean :: MonadRandom m => Int -> m Float -> m Flo...

I have a problem that I don't know how to reason about. I was just about to ask if somebody could help me with the specific problem, but it dawned on me that I could ask a more general question and...

One irritation with lazy IO caught to my attention recently import System.IO import Control.Applicative main = withFile "test.txt" ReadMode getLines >>= mapM_ putStrLn where getLines h = l...

Haskell has two left fold functions for lists: foldl, and a "strict" version, foldl'. The problem with the non-strict foldl is that it builds a tower of thunks: foldl (+) 0 [1..5] --> ((((0 + ...

There are two strict versions of zipWith function: 1) Really strict, elements of lists l1 and l2 get evaluated so their thunks do not eat all stack space (Don Stewart code) zipWith' f l1 l2 = [ f...

I made really time consuming algorithm which produces a short string as the result. When I try to print it (via putStrLn) it appears on the screen character by character. I did understand why that ...

Unboxed types, like Int#, and strict functions, like f (!x) = ..., are something different, but I see conceptual similarity - they disallow thunks/laziness in some way. If Haskell was a strict lang...