bash script to run yesod-dev's auto reload inside ghci

run-yesod-ghci.sh

#!/bin/bash

#
# bash script to run yesod-dev's auto reload inside ghci (faster template reloading)
#
# see also https://github.com/yesodweb/yesod/issues/754
#
# needs tmux and fswatch, tested on MacOS 10.10
#

function showHelp() {

  echo "Usage: $0 -w"
  echo ""
  echo "(You need tmux and fswatch)"

}


function startGhciYesodDev() {

  # start tmux with two windows:
  #   - ghci
  #   - fswatch (to trigger recompile on template change)
  tmux start-server
  tmux new-session -d -s ghci_server -n ghci
  tmux split-window -t ghci

  # start yesod with ghci
  tmux select-pane -t 0
  tmux send-keys -t ghci_server:ghci "ghci -XViewPatterns" C-m
  tmux send-keys -t ghci_server:ghci ":load Application" C-m
  tmux send-keys -t ghci_server:0 "import Network.Wai.Handler.Warp" C-m
  tmux send-keys -t ghci_server:0 "getApplicationDev >>= \(port, app) -> runSettings (setPort port defaultSettings) app" C-m

  # watch templates with 'fswatch'
  tmux select-pane -t 1
  tmux send-keys -t ghci:0 "fswatch -o ./templates | xargs -n1 $0" C-m

  tmux select-window -t ghci_server:ghci
  tmux attach-session -t ghci_server

}

function reloadTemplates() {
  # send reload&restart commands to ghci
  echo "$1 files changed, reloading..."
  tmux select-window -t ghci_server:ghci
  tmux select-pane -t 0

  tmux send-keys -t ghci_server C-c
  tmux send-keys -t ghci_server ":load Application" C-m
  tmux send-keys -t ghci_server "getApplicationDev >>= \(port, app) -> runSettings (setPort port defaultSettings) app" C-m
}

if [ "$1" == "" ]; then
  showHelp
elif [ "$1" = "-w" ]; then
  startGhciYesodDev
else
  reloadTemplates $1
fi