gistfile1.txt

callUpdateWith::UIEvent ->IO ()
callUpdateWith ev=do

    mw <-readIORef gWorld
    mu <-readIORef gUpdate
    ma <-readIORef gAssets
    
    -- is there a cleaner way to do this part:-
    -- I think of 'if let' in Rust (if let Some(a),Some(w),Some(u)) ...
    -- I also wonder if there's a way to 'pipe' the output of 'callUf u a ev w' into
    -- the assignments and 'putStrLn
    
    case (ma,mw,mu) of
      (Just a,Just w,Just u)->
        let (nw,nu,dbstr)= (callUf u a ev w) in
          (gWorld$=Just nw) >> (gUpdate$=Just nu) >> (putStrLn dbstr)
      _ -> return ()




{- was..
    (nw, nu,dbstr)<-return (
      case (ma,mw,mu) of
	(Just a,Just w,Just uf)->
          let (a,b,dbstr)=callUf uf  a ev w in (Just a, Just b, dbstr)
	_->(Nothing,Nothing,"no world set")
        )
    gWorld$=nw
    gUpdate$=nu
    putStrLn dbstr
-}

    return ()