[fexl]

Now on another topic which I find interesting, consider how the abstraction algorithm (conversion to combinators) can be simplified with the use of two helper functions L and R:

  \L = (\x\y\z (x z) y)  # send z to left side only
  \R = (\x\y\z x (y z))  # send z to right side only

Of course these can be defined in terms of S and C but I just implement them directly in the interpreter for efficiency.

Now let's abstract the Q definition using L and R in addition to S and C where possible:

  \Q = (\x\y x (y y))
  \Q = (\x R x (\y y y))
  \Q = (\x R x (S I I))
  \Q = (L (\x R x) (S I I))
  \Q = (L R (S I I))

That's much more compact than just using S and C alone.