[racket] how to improve performance by streamlining imports?

>> Perhaps you want to organize your programs in something like this fashion: 


Yes, I agree that's the better approach. It's also easier to automate — for instance, this macro makes the fast version of func available by default through (require module), and then the safe version as (require (submod module 'safe)).

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
#lang racket/base

(module+ safe (require racket/contract))

(define-syntax (define+provide+safe stx)
  (syntax-case stx ()
    [(_ (proc arg ... . rest-arg) contract body ...)
     #'(define+provide+safe proc contract
         (λ(arg ... . rest-arg) body ...))]
    [(_ name contract body ...)
     #'(begin
         (define name body ...)
         (provide name)
         (module+ safe 
           (provide (contract-out [name contract]))))]))

(define+provide+safe (func x)
  (expensive/c . -> . expensive/c)
  (do-things x)) 
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;




On Feb 21, 2014, at 6:00 PM, Matthias Felleisen <matthias at ccs.neu.edu> wrote:

> 
> On Feb 21, 2014, at 2:38 PM, Matthew Butterick wrote:
> 
>>> Rewriting to avoid a dependency does work, but usually only if you can
>>> avoid some large subsystem (such as the contract system) completely.
>> 
>> 
>> Contracts are a good example. Here's the vexing pattern that I've run into frequently
> 
> 
> Perhaps you want to organize your programs in something like this fashion: 
> 
> #lang racket
> 
> (module server racket
> 
>  (provide
>   (contract-out
>    (f (natural-number/c . -> . natural-number/c))))
> 
>  (module fast-server racket
>    (provide 
>     ;; Nat -> Nat 
>     f)
> 
>    (define (f i)
>      (- i 1)))
> 
>  (require (submod "." fast-server)))
> 
> (module safe-client racket
>  (require (submod ".." server))
>  (with-handlers ((exn:fail:contract? (compose displayln exn-message)))
>    (displayln (f 0))))
> 
> (module fast-client racket
>  (require (submod ".." server fast-server))
>  (displayln (f 0)))
> 
> (require 'safe-client)
> (require 'fast-client)