ghc

问题 I wrote a Haskell program that preforms a binary search on a list. At least that's what I thought it does. When I compiled the program with ghc v7.6.3 and ran the program I got the following output: progname: <<loop>> What on earth does this output mean? Does it mean I had an infinite loop that ghc optimized away? How am I supposed to debug this? 回答1: As several of the comments have said, this is the Haskell RTS detecting an infinite loop at run-time. It cannot always detect such loops, but

问题 Is there a reasonably fast way to extract the exponent and mantissa from a Number in Javascript? AFAIK there's no way to get at the bits behind a Number in Javascript, which makes it seem to me that I'm looking at a factorization problem: finding m and n such that 2^n * m = k for a given k . Since integer factorization is in NP, I can only assume that this would be a fairly hard problem. I'm implementing a GHC plugin for generating Javascript and need to implement the decodeFloat_Int# and

问题 I am trying to learn Haskell but it is a little hard as non of my bindings are remembered from the command line; output from my terminal below. > let b = [] > b [] > 1:b [1] > b [] I have no idea why this is like this can anyone please help. 回答1: What did you expect your example to do? From what you've presented, I don't see anything surprising. Of course, that answer is probably surprising to you, or you wouldn't have asked. And I'll be honest: I can guess what you were expecting. If I'm

问题 How can I see substitutions of variable names to their values in haskell? e.g. c2i zero ==> c2i (Chr (\x y -> y)) ==> (\x y -> y) (+ 1) 0 ==> 0 As explained in this answer. 来源： https://stackoverflow.com/questions/36650044/show-substitutions-in-ghci

问题 I am an absolute beginner. Going through LYAH using emacs. My current Set up: Ubuntu 12.04 LTS (Use Experience - beginner) GNU Emacs 23 (Use Experience - beginner) able to work in haskell major mode Finding difficult to follow instructions (to bring haskell libraries) at Point 2 described here. Also need guidance to enable Scion IDE. Problem: .hs code data Maybe a = Nothing | Just a While running the code, I get following error: Please ignore typo error, Originally posted: *Main> just "Haha"

问题 For the purposes of profiling a partially evaluated program, I'm interested in knowing the best way to terminate a GHC program. This is useful for profiling programs that take a long time to run, possibly as long as forever. With GHC 7.4.2, I was able to profile a non-terminating program by enabling profiling (-prof -auto-all) and running my program with +RTS -p . This generated incremental profiling data. The program could be killed with ^c , and the .prof file would contain data. In GHC 7.6

问题 I'm trying to install network and old-time with cabal-install. When I try to install either it fails with: setup.exe: The package has a './configure' script. This requires a Unix compatibility toolchain such as MinGW+MSYS or Cygwin. I do have MinGW, in fact it's the MinGW distributed along with GHC. I've also added the bin folder to my PATH. How can I fix this? what tool is the one actually running the configure files? maybe I need to get it? GHC 7.10.1 x64 cabal-install version 1.22.0.0

问题 I'm running GHC using Stack on Windows 10, and using Git Bash (MINGW64) for much of my daily workflow. That includes using GHC and GHCi, which generally works fine. However, when I run stack test from MINGW64, the output is garbled by ANSI color codes: $ stack test UC-0.1.0.0: test (suite: UC-test) [?25lSorting Group 1: [2K[1F prop1: [[92mOK, passed 100 tests[0m] [2K[1F prop2: [[92mOK, passed 100 tests[0m] Properties Total Passed [92m2[0m [92m2[0m Failed 0 0 Total [92m2[0m [92m2[0m [?25h

问题 I'm using vector library and trying to write simple function: import qualified Data.Vector.Generic as GV setCharges :: GV.Vector v Double => Network -> v Double -> Network setCharges n cs = n{nodes = GV.zipWith setCharge (nodes n) cs} With XFlexibleContexts ghc accepts type declaration but complain near cs varibale Could not deduce (v ~ Vector) I have nodes n :: Data.Vector.Vector Node setCharge :: Node -> Double -> Node Don't really get, what the problem. 回答1: It's just what GHC says: the

问题 I want to create a haskell interpreter that I can use from C++ on linux. I have a file FFIInterpreter.hs which implements the interpreter in haskell and exports the functions via FFI to C++. module FFIInterpreter where import Language.Haskell.Interpreter import Data.IORef import Foreign.StablePtr import Foreign.C.Types import Foreign.C.String import Control.Monad import Foreign.Marshal.Alloc type Session = Interpreter () type Context = StablePtr (IORef Session) foreign export ccall