ghci

Suppose I am given a source file called MyModule.hs and inside it the module declaration is module My.Module where ... (note: not module MyModule where ... ). I am not permitted to alter this source file or change the directory structure where the file resides. From reading some docs about importing modules in GHCi , it looks like there are ways to import by file name (e.g. either import or :load ), but not any ways to specify a module name that will be searched for in all files of the local directory. Is there a way to import My.Module in GHCi without doing it by specifying the file's name

I am following https://en.wikibooks.org/wiki/Haskell/Understanding_monads/State , and randomIO prints an integer in ghci directly. Given its type is polymorphic, how does ghci know it's Int here? Are there some special rules for type inference in ghci ? GHCi> :m System.Random GHCi> :t randomIO randomIO :: Random a => IO a GHCi> randomIO -1557093684 GHCi> randomIO 1342278538 I suppose it is just simple Monomorphism restriction . Polymorphic types such as Num a => a are handled like Integer if actual type is not specified. Probably this rule also works in ghci and you see integer type instead of

I need to write on a module to be run on GHCi, with a function composition to the same function. This (The classic fog(x) = f(g(x)) ) runs: (.) f g = (\x -> f (g x)). The problem appears when I try to write it like this (.) f f = (\x -> f (f x)). (fof(x) = f(f(x))) GHCi says: "Conflicting definitions for `f' Bound at: Lab1.hs:27:9 Lab1.hs:27:12" Line 27:9 appear on the first time f and line 27:12 appear f again. Why doesn't Haskell understand (.) f f = (\x -> f (f x)) ? Will Ness In Haskell, arguments to a function must have unique names. Using the same name for another argument is not allowed

Here's the error I see when trying to load a .hs file into ghci. >Loading package http-enumerator-0.7.1.1 ... linking ... done. >Loading package double-conversion-0.2.0.1 ... can't load .so/.DLL for: stdc++ ?>>> (libstdc++.so: cannot open shared object file: No such file or directory) Further investigation reveals I have multiple stdc++ libraries installed >locate libstdc++.so >/usr/lib/libstdc++.so.6 >/usr/lib/libstdc++.so.6.0.14 >/usr/lib/gcc/x86_64-linux-gnu/4.4/libstdc++.so >/usr/lib32/libstdc++.so.6 >/usr/lib32/libstdc++.so.6.0.14 I thought maybe I could make a symlink to what it wants,

Using the low-level GNU Science Library bindings Bindings.Gsl.RandomNumberGeneration , I'm running into this odd type behavior in GHCi where binding changes return type from a peek into GHC.Prim.Any . I'm trying to understand why since I can't use the c'rng_alloc unless I retain the type of pointer to an rng . For eample: λ> :t c'gsl_rng_alloc c'gsl_rng_alloc :: Ptr C'gsl_rng_type -> IO (Ptr C'gsl_rng) λ> :t p'gsl_rng_mt19937 p'gsl_rng_mt19937 :: Ptr (Ptr gsl_rng_type) λ> :t peek p'gsl_rng_mt19937 peek p'gsl_rng_mt19937 :: IO (Ptr gsl_rng_type) λ> x <- peek p'gsl_rng_mt19937 λ> :t x x :: Ptr