phoityne-vscode: Haskell Debug Adapter for Visual Studio Code.

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Dependencies aeson, base (>=4.7 && <5), bytestring, Cabal, cmdargs, conduit, conduit-extra, containers, data-default, directory, filepath, fsnotify, hslogger, lens, MissingH, mtl, parsec, process, resourcet, safe, safe-exceptions, split, text, transformers [details]
License BSD-3-Clause
Copyright 2016-2019 phoityne_hs
Author phoityne_hs
Category Development
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Uploaded by phoityne_hs at Sun Feb 3 03:14:48 UTC 2019
Distributions NixOS:
Executables phoityne-vscode
Downloads 4795 total (324 in the last 30 days)
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Docs not available [build log]
Last success reported on 2019-02-03 [all 3 reports]


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For package maintainers and hackage trustees

Readme for phoityne-vscode-

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Install phoityne-vscode from hackage.

Especially for GHC8

Install phoityne-vscode and haskell-dap.
In the launch.json, add "--with-ghc=haskell-dap" to ghciCmd variable.

> stack install phoityne-vscode haskell-dap


  • The source file extension must be ".hs"
  • Can not use STDIN handle while debugging.
  • Using GHC7, see the README.


Continue & Steps



The variable added to watch will be forced.




Break condition


Console output


Quick Start

This is a new experimental feature.
Note!!, This function will automatically change the .vscode / launch.json file. 06_quick_start.gif

Shortcut keys

When you start debugging for the first time, .vscode/tasks.json will be created automatically. Then you can use F6, F7, F8 shortcut keys.

  • F5 : start debug
  • F6 : show command menu (for stack watch)
  • Shift + F6 : stop stack watch
  • F7 : stack clean & build
  • F8 : stack test
  • F9 : put a breakpoint on the current line
  • Shift + F9 : put a breakpoint on the current column

While debugging, you can use F5, F9, F10, F11 shortcut keys.

  • F5 : jump to next bp
  • F9 : put bp on the line
  • Shift + F9 : put bp on the column
  • F10 : step next
  • F11 : step into



|NAME|REQUIRED OR OPTIONAL|DEFAULT SETTING|DESCRIPTION| |:--|:--:|:--|:--| |startup|required|${workspaceRoot}/test/Spec.hs|debug startup file, will be loaded automatically.| |startupFunc|optional|"" (empty string)|debug startup function, will be run instead of main function.| |startupArgs|optional|"" (empty string)|arguments for startup function. set as string type.| |ghciCmd|required|stack ghci --test --no-load --no-build --main-is TARGET --ghci-options -fprint-evld-with-show|launch ghci command, must be Prelude module loaded. For example, "ghci -i${workspaceRoot}/src", "cabal exec -- ghci -i${workspaceRoot}/src"| |ghciPrompt|required|H>>=|ghci command prompt string.| |ghciInitialPrompt|optional|"Prelude> "|initial pormpt of ghci. set it when using custom prompt. e.g. set in .ghci| |stopOnEntry|required|true|stop or not after debugger launched. |mainArgs|optional|"" (empty string)|main arguments.| |logFile|required|${workspaceRoot}/.vscode/phoityne.log|internal log file.| |logLevel|required|WARNING|internal log level.|

changing ghci initial prompt

If you change ghci prompt in .ghci file, or ghci prompt is changed from "Prelude>" by applying NoImplicitPrelude extension, set the initial prompt variable to same prompt string.

% diff .vscode/launch.json.old .vscode/launch.json
<             "ghciInitialPrompt": "Prelude> "      // default value.
>             "ghciInitialPrompt": "> "             // e.g.

Make sure needs of the last space, and don't forget adding it.

setting the startup hs file

Set the startup variable to the path of .hs file in which main function is defined.

% diff .vscode/launch.json.old .vscode/launch.json
<             "startup": "${workspaceRoot}/test/Spec.hs",    // default value.
>             "startup": "${workspaceRoot}/app/run.hs",     // e.g.

setting the startup function

If you want to run the specific function instead of main function, set the startupFunc variable.
For example, when specifying the following startDebug function,

startDebug :: String -> IO ()
startDebug name = do
  putStrLn "hello"
  putStrLn name 

set the valiavles in the launch.json file.

% diff .vscode/launch.json.old .vscode/launch.json
<             "startupFunc": "",    // default value.
<             "startupArgs": "",    // default value.
>             "startupFunc": "startDebug",       // e.g.
>             "startupArgs": "\"phoityne\"",     // e.g.

changing log level

For debugging phoityne itself, change the log level to DEBUG.
Adding Issue with the debug log.

% diff .vscode/launch.json.old .vscode/launch.json
<             "logLevel": "WARNING",               // default value.
>             "logLevel": "DEBUG",                 // e.g.


|TASK NAME|REQUIRED OR OPTIONAL|DEFAULT SETTING|DESCRIPTION| |:--|:--:|:--|:--| |stack build|required|stack build|task definition for F6 shortcut key.| |stack clean & build|required|stack clean && stack build|task definition for F7 shortcut key.| |stack test|required|stack test|task definition for F8 shortcut key.| |stack watch|required|stack build --test --no-run-tests --file-watch|task definition for F6 shortcut key.|


Thank you for your contribution for this project.