[tromp]

> The pattern \lambda a. \lambda b. \lambda w. \lambda x. \lambda y. yλa.λb.λw.λx.λy.y is noticable in many places in lambdalisp.pdf, since isnil is used a lot of times in LambdaLisp.

Sadly, this heavy use of the isnil operator derived in section [1] adds a lot of unnecessary verbosity, since instead of writing

    isnil list
      result1
      (let { head = car list, tail = cdr list} in result2)

one can simply write

    list
      (\head \tail \_ . result2)
      result1

[1] https://woodrush.github.io/blog/lambdalisp.html#deriving-isn...