Try Eff online!

      
On the left-hand side, you see two text areas. The top one contains your source code, and the bottom one is the interactive toplevel. You execute the source code in the toplevel using the button between them. This web-based Eff toplevel is compiled using Js_of_ocaml and is very much based on the toplevel example included with Js_of_ocaml.

      
Load examples

      

      
Toplevel commands

      

        
          

            Enter/Return
            Submit code
          

          

            Ctrl + Enter
            Newline
          

          

            Up / Down
            Browse history
          

          

            Ctrl + l
            Clear display
          

          

            Tab
            Indent code