Here's a quick and dirty way to set up a musl based chroot environment using the experimental gentoo image for x86_64:
CHROOT_PATH=/var/tmp/gentoo-musl
IMAGE_URI=http://distfiles.gentoo.org/experimental/amd64/musl/stage3-amd64-musl-vanilla-XXXXXX.tar.bz2
GHC_URI=https://github.com/redneb/ghc-alt-libc/releases/download/XXX/ghc-YYY
# setup the chroot environment:
mkdir "$CHROOT_PATH"
cd /var/tmp
wget "$IMAGE_URI"
tar xjf stage3-*-musl-vanilla-*.tar.bz2 -C "$CHROOT_PATH"
wget "$GHC_URI"
mv ghc-*-linux-musl.tar.xz "$CHROOT_PATH/var/tmp"
# enter the chroot environment:
for x in dev proc sys; do mount --bind /$x "$CHROOT_PATH/$x"; done
cp -L /etc/resolv.conf "$CHROOT_PATH/etc"
chroot "$CHROOT_PATH" /bin/bash -l
PS1="(chroot) $PS1"
# fetch the gentoo package db for the first time (slow):
emerge-webrsync
# enable static libraries (*.a), which are disabled by default:
sed -ie 's/USE="/USE="static-libs /' /etc/portage/make.conf
# reinstall/recompile gmp so that its static libs are available:
emerge --oneshot dev-libs/gmp
# install ghc:
tar xJf /var/tmp/ghc-*-linux-musl.tar.xz -C /tmp
cd /tmp/ghc-*;
./configure --prefix=/opt/ghc; make install
# compile a hello world:
cd /tmp
echo 'main = putStrLn "Hello world"' > test.hs
/opt/ghc/bin/ghc --make -O -optl-static test.hs
./test
file ./test
Of course, using chroot like that is insecure, don't use it to install packages from hackage. A similar process can be used with LXC or systemd-nspawn.