Hello from ATStead!

The toy language

Commands

• arrows: navigate (down: move to the first child)
• i: insert "if" at focus point
• h: replace focus point with a hole
• v: insert "var" at focus point
• 0-2: insert a digit constant at focus point
• l: insert a "lam" at focus point
• space: insert an "app" at focus point
• 9-0: insert left-right parenthesis

Things to try

• v p v: var+var
• v m v p v m v: var*var+var*var
• i v v v p v: (if var then var else var) + var
• l v v p v m v: lam var . var + var * var
• 9 v p v 0 m 9 v p v 0: (var + var) * (var + var)