安装yesod的问题

Question

我想yesod在我的业余时间安装以了解一些关于网络和在Haskell上玩一下但是当我这样做时:

> cabal install yesod
Resolving dependencies...
cabal: cannot configure cprng-aes-0.2.2. It requires crypto-api >=0.8
For the dependency on crypto-api >=0.8 there are these packages:
crypto-api-0.8. However none of them are available.
crypto-api-0.8 was excluded because skein-0.1.0.1 requires crypto-api ==0.6.*
crypto-api-0.8 was excluded because crypto-api-0.6.4 was selected instead
crypto-api-0.8 was excluded because clientsession-0.7.3.1 requires crypto-api
>=0.6.4 && <0.7

但我认为我安装了正确的软件包

cabal list cprng-aes skein crypto-api clientsession
* clientsession
    Synopsis: Securely store session data in a client-side cookie.
    Default available version: 0.7.3.1
    Installed versions: 0.7.3.1
    Homepage: http://github.com/snoyberg/clientsession/tree/master
    License:  BSD3

* cprng-aes
    Synopsis: Crypto Pseudo Random Number Generator using AES in counter mode.
    Default available version: 0.2.2
    Installed versions: 0.2.2
    Homepage: http://github.com/vincenthz/hs-cprng-aes
    License:  BSD3

* crypto-api
    Synopsis: A generic interface for cryptographic operations
    Default available version: 0.8
    Installed versions: 0.6.4, 0.8
    Homepage: http://trac.haskell.org/crypto-api/wiki
    License:  BSD3

* crypto-api-tests
    Synopsis: A test framework and KATs for cryptographic operations.
    Default available version: 0.1
    Installed versions: [ Not installed ]
    Homepage: http://trac.haskell.org/crypto-api/wiki
    License:  BSD3

* hack-middleware-clientsession
    Synopsis: Middleware for easily keeping session data in client cookies.
    Default available version: 0.0.1
    Installed versions: [ Not installed ]
    Homepage: http://github.com/snoyberg/hack-middleware-clientsession/tree/master
    License:  BSD3

* skein
    Synopsis: Skein, a family of cryptographic hash functions. Includes
              Skein-MAC as well.
    Default available version: 0.1.0.1
    Installed versions: 0.1.0.1
    License:  BSD3

我不很了解cabal install,但似乎都crypto-api >=0.8和<7要求,这似乎是不可能的.

Answer 1

Crypto-API维护者在这里.

问题

问题是包是互斥的.最新的cprng-aes需要crypto-api版本>= 0.8.最新的绞痛需要crypto-api 0.6.*.所以我们想要发生的事情是绞肉开发人员(我将通过电子邮件发送)来更新包裹.

目前

到那时,您需要安装相关软件包的旧版本.尝试类似的东西:

cabal install yesod 'crypto-api == 0.6.4' 'cprng == 0.2.1'

我认为语法是正确的.如果没有,你可以随时做:

cabal install yesod crypto-api-0.6.4 cprng-0.2.1

社区如何避免这种情况

从长远来看,我希望cabal会变得更好并自动找到兼容的版本,就像我上面所做的那样.除了每个人都提到并且没有人实现的这种集合改进之外,对于软件包维护者而言,尝试在其构建版本上保持一致的下限是很好的.如果cprng-aes仍然被接受,crypto-api >= 0.5那么我认为这将由cabal安装.这对包维护者有点要求,但他们可以使用CPP和{MAX,MIN}_VERSIONcabal提供的宏来完成.

编辑:更新 Felipe已更新绞纱并上传到hackage.迈克尔已经更新了客户评论,并且看到他是Yesod维护者并且已经参与了电子邮件对话,我相信他很快就会把它上传到hackage.应该在您阅读此消息时修复问题,只需运行:

 cabal update ; cabal install yesod

经过反思,我看到crypto-api中的主要版本流量有多大会导致社区其他人.我不知道如何处理这个问题.我本可以观察到"如果我做出这个改变,没有人会受到影响"并且只是打破了PVP.OTOH,如果我在没有遵循PVP的情况下打破某些代码,那么他们就有理由感到不安.有社区评论吗？