有没有办法编写ghci会话脚本? [英] Is there a way to script a ghci session?

问题描述

我的目标是通过一些步骤使 ghci 从bash脚本运行，然后干净地退出.在线评论说为此使用 runhaskell .

My goal is to pipe some steps for ghci to run from a bash script and then exit cleanly. The commentary online says to use runhaskell for this.

这是我要运行的命令:

ghci> import System.Random 

ghci> random (mkStdGen 100) :: (Int, StdGen) 

预期结果类似于:

(-3633736515773289454,693699796 2103410263)

当我将其放入文件 randomtest.hs 并使用 runhaskell 执行该文件时，出现以下错误:.

When I drop this into a file randomtest.hs and execute it with runhaskell I get the following error:.

randomtest.hs:3:1: error:
    Invalid type signature: random (mkStdGen 100) :: ...
    Should be of form <variable> :: <type>

似乎我不能使用 runhaskell 方法盲目执行 ghci 输入.

It seems I can't use the runhaskell method to blindly execute ghci inputs.

现在解决此问题的方法是向传递给 runhaskell 的文件中添加额外的命令:

Now the way to work around this is to add extra commands to the file that is passed to runhaskell:

main = do print (random (mkStdGen 100) :: (Int, StdGen))

我的目标是针对我正在使用的haskell课程自动执行ghci工作.我希望能够从bash脚本中运行ghci命令-以ghci期望的格式运行，并使其从ghci干净退出(或运行它的任何方式).

My goal is to automate the running of ghci work for a haskell course I'm using. I want to be able to run the ghci command from a bash script - in the format that ghci expects, and have it cleanly exit from ghci (or whatever runs it).

我的问题是:是否可以编写ghci会话脚本?

推荐答案

您将要使用期望，您可以使用简单的命令以交互方式控制REPL.该脚本可以满足您的要求:

You'll want to use expect for that, it allows you to interactively control a REPL with simple commands. This script does what you want:

#!/usr/bin/env expect

log_user 0
spawn ghci
log_user 1

expect ".*> "
send ":set prompt \"ghci> \"\n"

expect "ghci> "
send "import System.Random\n"
expect "ghci> "
send "random (mkStdGen 100) :: (Int, StdGen)\n"

interact

运行此操作将为您提供以下内容:

Running this gives you the following:

$ ./ghci-interactive
GHCi, version 8.0.2: http://www.haskell.org/ghc/  :? for help
Prelude> :set prompt "ghci> "
ghci> import System.Random
ghci> random (mkStdGen 100) :: (Int, StdGen)
(-3633736515773289454,693699796 2103410263)
ghci> 

注意:您可能需要对此进行一些调整，以防止用户在〜/.ghci 中设置提示.

Note: You might need to adjust this a bit to be resistant to users setting the prompt in ~/.ghci.

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