In Haskell, how do I install the encoding package on Windows?

Question

I'm a total newb with haskell and I'm making a trivial project but I needed to run cabal install encoding. But, when I did, it gave me this error:

Configuring encoding-0.6.7.2...
setup.exe: Missing dependency on a foreign library:
* Missing (or bad) header file: system_encoding.h
This problem can usually be solved by installing the system package that
provides this library (you may need the "-dev" version). If the library is
already installed but in a non-standard location then you can use the flags
--extra-include-dirs= and --extra-lib-dirs= to specify where it is.
If the header file does exist, it may contain errors that are caught by the C
compiler at the preprocessing stage. In this case you can re-run configure
with the verbosity flag -v3 to see the error messages.
cabal.exe: Error: some packages failed to install:
encoding-0.6.7.2 failed during the configure step. The exception was:
ExitFailure 1

How do fix this problem?

Answer 1

TL;DR: cabal install encoding -f-systemencoding

---

I found a few forum posts on this topic. The most important thing said was

The missing header is langinfo.h - where it originates I don't know, as I don't have it with either Msys/MinGW or Cygwin and my Cygwin is pretty large these days.

From there, I looked on the Cygwin website for where langinfo.h is. Turns out it comes with the default install of Cygwin. And this is its path:

usr/include/langinfo.h

So I installed Cygwin, (actually I already had it installed) and then I ran cabal install like this:

cabal install encoding --extra-include-dirs='C:\cygwin\usr\include'

That registered the package without issue.

---

Update

Although this does let you register the package, you can't use it. When I tried to GHCi gave me this error:

Loading package encoding-0.6.7.2 ... linking ... ghc: unable to load package `encoding-0.6.7.2'

I am now stuck again.

Update 2

I got some help on IRC from a gentleman named fryguybob. This is another way you can install it: cabal install encoding -f-systemencoding. That worked for me