try-reflex

#!/usr/bin/env bash
set -eu

DIR=$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )

. "$DIR/common-setup.sh"

ROOT_PERMISSION_FIX_SUGGESTION="please use your operating system's \"repair permissions\" feature, if it has one, or manually remove write permissions for your user from the '/' directory."

if [ -e /homeless-shelter ] ; then
  echo "It looks like your system has a directory or file at '/homeless-shelter'.  This will cause the try-reflex build to fail, because the Nix package manager assumes that /homeless-shelter does not exist and cannot be created."
  echo
  echo "If you intentionally created /homeless-shelter, please submit an issue at $REPO/issues, and we will try to find a workaround for this situation.  However, usually, this directory is created by accident when a Nix script is run by a user who has write permissions to the root directory."
  echo
  echo "If this is the case, please remove the /homeless-shelter directory, then ensure that your root directory is not writable by the current user.  To do this, $ROOT_PERMISSION_FIX_SUGGESTION"
  exit 1
elif mkdir /homeless-shelter 2>/dev/null ; then
  rmdir /homeless-shelter
  echo "It looks like your filesystem's root directory is writable by the current user.  This will cause nix to fail building try-reflex, and may also indicate a security vulnerability.  Note that you should not run try-reflex as root."
  echo
  echo "To fix this problem, $ROOT_PERMISSION_FIX_SUGGESTION"
  exit 1
fi

echo "Entering the reflex sandbox..."

# TODO: Use a better check that actually checks for each platform's availability
if [ ! "$(nix-instantiate --eval -E '(import <nixpkgs> {}).stdenv.isDarwin')" = "true" ] ; then
SUGGESTION_GHC=$(cat <<EOF
To run a simple GUI as a native binary:
$ ghc -XOverloadedStrings -e 'import Reflex.Dom' -e 'mainWidget $ text \"Hello, world!\"'

Or to see a more complex native binary GUI example (based on the source at https://github.com/reflex-frp/reflex-todomvc/blob/master/src/Main.hs):
$ reflex-todomvc
EOF
)
else
SUGGESTION_GHC=""
fi

SUGGESTION_GHCJS=$(cat <<EOF2
To create a simple web GUI:
$ cat >hello.hs <<EOF
{-# LANGUAGE OverloadedStrings #-}
import Reflex.Dom
main = mainWidget $ text \"Hello, world!\"
EOF
$ ghcjs hello.hs
Then navigate your browser to file://$(pwd)/hello.jsexe/index.html

Or to see a more complex GUI example (based on the source at https://github.com/reflex-frp/reflex-todomvc/blob/master/src/Main.hs), navigate your browser to file://$(nix-build $NIXOPTS --no-out-link "$DIR" -A ghcjs.reflex-todomvc)/bin/reflex-todomvc.jsexe/index.html
EOF2
)

INFO=$(cat <<EOF

You are now in a shell with access to the Reflex functional reactive programming engine.

$SUGGESTION_GHC

$SUGGESTION_GHCJS
EOF
)

nix-build "$DIR/shell.nix" --drv-link "$DIR/gc-roots/shell.drv" $NIXOPTS --indirect --add-root "$DIR/gc-roots/shell.out" >/dev/null
terminate_logging
nix-shell "$DIR/gc-roots/shell.drv" $NIXOPTS --command "echo \"$INFO\" ; return" "$@"