Haskell堆栈版本依赖性

Question

堆栈新手。 我开始构建并发的web scraper ，并运行stack new my-project simple 。 在my-project.cabal我必须插入hxt，url，http和maybet的依赖项。

executable my-project
  hs-source-dirs:      src
  main-is:             Main.hs
  default-language:    Haskell2010
  build-depends:       base >= 4.7 && < 5,
                       time,
                       hxt,
                       http,
                       maybet

当我运行stack build ，我得到了：

Error: While constructing the build plan, the following exceptions were encountered:

In the dependencies for my-project-0.1.0.0:
    http must match -any, but the stack configuration has no specified version
    maybet must match -any, but the stack configuration has no specified version
needed since my-project is a build target.

Some potential ways to resolve this:

  * Set 'allow-newer: true' to ignore all version constraints and build anyway.

  * You may also want to try using the 'stack solver' command.

在可执行指令下插入allow-newer: true似乎不起作用，并添加诸如http == *版本后缀会导致解析错误，并给它提供http == 4000.3.9,因为黑客文档给我的http must match ==4000.3.9, but the stack configuration has no specified version

有没有一种简单的方法可以告诉集团文件我需要最新版本？

Answer 1

Hackage中没有名为http的软件包。 但是您有一个名为HTTP的包。

因此，固定软件包名称应该可以为您解决问题。

（此外，博客文章似乎已经过时了，最近进行HTTP请求的标准方法是通过管道/ wreq / req）。