Thank you, Robby,
This clarifies it a little bit. So far I've avoided reading about the racket
module system in details, but I think now is as good time as ever.
April 7, 2021 10:40 PM, "Robby Findler" mailto:ro...@cs.northwestern.edu?to=%22Robby%20Findler%22%20)>
wrote:
The short answer: you
I think "define/contract" protects a function from other incorrect calls
from the same module. So your "define/provide/contract" is not really
"define/contract" + "provide". Here is an example illustrating the
problem, where the call to "bar" correctly reports the contract violation,
but the
The idea is that a contract violation is not merely telling you "oh,
someone said that you should get an integer? here and you didn't." That is
what an assert macro might do. But contracts offer more.
Contracts are also giving you information to help you hone in on where the
error actually is in
Clueless newb here. Wait, why can't we have both? As a joe programmer
on the street I would want the blame to be on b.rkt, and also on any
function calling f() incorrectly from inside a.rkt. Reading this
thread it sounds to me like that's not easily available?
On Wed, Apr 7, 2021 at 4:22 PM Robby
No, I don't think it is a bad move if that's your goal! (I usually work at
the file-level granularity but different code calls for different things.)
I inferred from epi's message that that wasn't what was going on (perhaps
incorrectly).
Robby
On Wed, Apr 7, 2021 at 4:37 PM David Storrs wrote:
I've always liked define/contract because it guarantees the safety of
the function from erroneous calls by other functions in the module,
which helps with debugging and testing. It sounds like you think
that's a bad move?
On Wed, Apr 7, 2021 at 4:35 PM Robby Findler wrote:
>
> The short answer:
It is worth noting that it is relatively easy to implement a
define/provide/contract syntax without any problems. In my two most
active projects I use it extensively. In one case even with
scribble/srcdoc to keep the contracts, scribblings and implementation in
one place.
The simplest version:
The short answer: you probably should use (provide (contract-out))
instead of define/contract.
The slightly longer answer: when you write a contract, you are not just
describing what the legal inputs and outputs are, you are also establishing
a *boundary* between two regions of code. In the
Hello Racket users,
I am trying to understand a contract violation message that I am getting.
Here is the file a.rkt:
#lang racket
(provide f)
(define/contract (f a)
(-> boolean? any/c)
'())
and this is b.rkt:
#lang racket
(require "a.rkt")
(f 3)
I would
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