Elm - Taming Callbacks(Graphics.Element, Mouse(isDown), Signal(map2))

Seven More Languages
in Seven Weeks

開発環境

• OS X El Capitan - Apple (OS)
• Emacs (Text Editor)
• Elm (プログラミング言語)

Seven More Languages in Seven Weeks (Bruce Tate (著)、Ian Dees (著)、Frederic Daoud (著)、Jack Moffitt (著)、Pragmatic Bookshelf)のChapter 3(Elm)、Day 2(Taming Callbacks)、Do (Easy)(No. 3307).を取り組んでみる。

Do (Easy)(No. 3307)

コード(Emacs)

import Graphics.Element exposing (show)
import Mouse

positionAndPressed position down =
  show (if down
        then ((toString position) ++ " clicked!")
        else (toString position))
                                          
main = Signal.map2 positionAndPressed Mouse.position Mouse.isDown

入出力結果(Emacs, Terminal, elm repl)

$ elm-make sample_easy.elm --output sample_easy.html
Success! Compiled 1 modules.
Successfully generated sample_easy.html
$