如何避免在这个 cabal 文件中重新编译? [英] How to avoid recompiling in this cabal file?

问题描述

我一直在研究这个 Haskell 项目，我有一个用于它的 cabal 文件.现在，我的项目被构建为一个实现简单解释器的库.我还有一个非常短的 Main 文件，需要将其构建到可执行文件中才能调用库.我想做的是:

I've been working on this Haskell project, and I have a cabal file for it. Now, my project is structured as a library that implements a simple interpreter. I also have a very short Main file which needs to be build into an executable to call the library. What I want to do is:

1) 编译库并公开一些模块

1) compile the library and expose some of the modules

2) 编译可执行文件

我有一个可以运行的 cabal 文件，并且似乎可以做到这一点.问题是当它编译可执行文件时，它重新编译所有已经在步骤 (1) 中编译的模块.我不太明白它为什么这样做 - 除了创建两个单独的 cabal 文件之外，有没有办法阻止它?

I have a cabal file that works and seems to do this. The problem is that when it compiles the executable it recompiles all the modules which have already been compiled in step (1). I don't quite understand why it does this - is there any way to stop it, short of creating two separate cabal files?

我真的不想创建两个单独的 cabal 文件，因为 cabal 似乎不喜欢将两个 cabal 文件放在同一目录中，而且我真的不想为它们设置单独的项目目录第二步，因为它基本上只是编译一个文件.

I don't really want to create two separate cabal files, because cabal doesn't seem to like having both the cabal files in the same directory, and I don't really want to set up a separate project directory for the second step, since it basically just amounts to compiling a single file.

cabal-version:      >= 1.6
build-type:         Simple
name:               HaSC
version:            0.2.3
license:            OtherLicense
category:           Language
author:             Chris B
maintainer:         Chris B
copyright:          Chris B 2010 - 2011
synopsis:           (HA)skell (S)ound (C)hange applier (HaSC) library
description:        HaSC implements a little language for applying sound changes to words
homepage:           http://www.chrisdb.me.uk/redmine/projects/haskell-sound-change
stability:          Alpha
data-files:         doc/HaSCDoc.pdf
license-file:       LICENSE

library
    build-depends:
        base >= 4.3,
        containers >= 0.3,
        parsec >= 3,
        parallel >= 3.1,
        deepseq >= 1.1,
        mtl >= 1.1, 
        transformers >= 0.2,
        text >= 0.10,
        text-icu >= 0.6.3,
        pretty >= 1,
        directory >= 1.1,
        filepath >= 1.2
    hs-source-dirs:  src
    exposed-modules: HaSC.IO.Disk,
                     HaSC.IO.Memory,
                     HaSC.Exec
    other-modules:   HaSC.AST,
                     HaSC.IO,
                     HaSC.IdentMap,
                     HaSC.Parse,
                     HaSC.Regex,
                     HaSC.Representation,                     
                     HaSC.Transformations,
                     HaSC.Search,
                     HaSC.State

executable HaSC
    GHC-Options: -rtsopts
    hs-source-dirs:  src
    main-is:         Main.hs    

推荐答案

在你的可执行部分，在 Build-Depends 中添加库，以便可执行依赖于该库.

In your executable section, add the library in Build-Depends so that the executable depends on the library.

不过，有一个小问题:您还必须将可执行文件的 Main.hs(以及特定于可执行文件的任何其他源文件)移动到不同的子目录并指定不同的 Hs-Source-Dirs 以便它不会通过位于同一文件夹中来获取库模块.

There's a small gotcha, though: You also have to move the Main.hs of the executable (and any other source files specific to the executable) to a different subdirectory and specify a different Hs-Source-Dirs so that it doesn't pick up the library modules by being in the same folder.

executable HaSC
    Build-Depends: HaSC
    Main-Is: Main.hs
    Hs-Source-Dirs: foo -- Directory you moved Main.hs to

为此，您需要指定 Cabal-Version >= 1.8.有关详细信息，请参阅 Cabal 票 #89.

For this to work, you will need to specify Cabal-Version >= 1.8. See Cabal ticket #89 for the details.

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