M-expression desugaring

m-expr.txt

f x y z  =>  f[x, y, z]

f : g : x  =>  f[g[x]]

{x, y, z}  =>  Do[x, y, z]

----------------

If (x == 0) {
  Say['Hello!']
} {
  Say['Ducks']
}

=>

If[==[x, 0], Do[Say['Hello!'], Do[Say['Ducks']]]

----------------

Rec {
  odd = Fn[x]: If (x == 0) False even[x - 1]
  even = Fn[x]: If (x == 0) True odd[x - 1]
}

=>

Rec[Do[
  =[odd, Fn[x][If[==[x, 0], False, even[-[x, 1]]]]],
  =[even, Fn[x][If[==[x, 0], True, odd[-[x, 1]]]]]
]]