This is used for functions with a single argument imported with
`require/typed`, and avoids unneccessary checks. This produces a
3x speedup on the following benchmark:
#lang racket/base
(module m racket/base
(provide f)
(define (f x) x))
(module n typed/racket/base
(require/typed
(submod ".." m)
[f (-> Integer Integer)])
(time
(for ([x (in-range 1000000)])
(f 1) (f 2) (f 3) (f 4))))
(require 'n)
on top of the previous improvment from using `unsafe-procedure-chaperone`
and `procedure-result-arity`.
When exporting row polymorphic functions from TR, just
use absent clauses to ensure that TR won't accidentally
try to add pre-existing fields/methods. No sealing is
needed because the typechecker enforces parameteric use
of the class.
