This tiny script goes into your Hammerspoon configuration and it hooks on the lid open/close event

hammerspoon_sleep_script.lua

function sleepWatch(eventType)
    local action = "unknown"
	if (eventType == hs.caffeinate.watcher.systemWillSleep) then
		hs.alert.show("Going to sleep!")
		host = hs.host.localizedName()
        	action = "sleep"
	elseif (eventType == hs.caffeinate.watcher.systemDidWake) then
		hs.alert.show("Waking up!")
        	action = "awake"
	end

    -- write current state of laptop lid to file
    if (action ~= "unknown") then
        filename = string.format("%s/mylaptoplid.txt", os.getenv( "HOME" ))
        local f = assert(io.open(filename, "a+"))
        local tstamp = os.date("%d/%m/%y %H:%M:%S")
        local s = string.format("%s %s\n", tstamp, action)
        f:write( s )
        f:flush()
        f:close()
    end
end

local sleepWatcher = hs.caffeinate.watcher.new(sleepWatch)
sleepWatcher:start()