Haskell ESTGi Debugger

Table of Contents

1. Introduction
2. Overview
3. Setup
4. Development

Introduction

This repository contains the components for Haskell debugging based on the Debug Adapter Protocol (DAP).

• dap/: Language and backend independent DAP library
• dap-estgi-server/: DAP server for External STG Interpreter (DAP-ESTGi)
• dap-estgi-vscode-extension/: VSCode extension to support Haskell debugging using DAP-ESTGi server

Overview

The dap-estgi-vscode-extension turns VSCode into a Haskell debugger. VSCode offers a nice debugger UI while the debugger features are provided by the External STG Interpreter DAP Server.

flowchart LR
	subgraph User Interface
	A(VSCode) -.- |Plugin API| B(DAP ESTGi Extension)
	end
	B <-->|DAP via network| C(DAP ESTGi Server)
	subgraph Debugger
	C -.- |HS library API| D(External STG Interpreter)
	end

Loading

The dap-estgi-server and dap-estgi-vscode-extension are application specific components, while the dap library is designed to be application independent to support any project that needs a simple DAP framework.

Setup

• Enable allow breakpoints everywhere option in VSCode settings.

Install Haskell ESTGi Debugger Dependencies

• Run (cd haskell-estgi-debugger ; stack install zip-cmd)
• Ensure libgmp is installed (e.g. if using homebrew, brew install gmp)

Run dap-estgi-extension

• Run (cd dap-estgi-vscode-extension ; npm install)
• Open dap-estgi-vscode-extension folder by using the Files/Open Folder menu.
• Open the src/extension.ts file.
• Press F5 to run the extension in a new VSCode [Extension Development Host] window.

Start dap-estgi-server

(cd dap-estgi-server ; stack run)

Note: If using Darwin OSX and you receive

external-stg-interpreter> * Missing (or bad) C library: omp
external-stg-interpreter> This problem can usually be solved by installing the system package that
external-stg-interpreter> provides this library (you may need the "-dev" version). If the library is
external-stg-interpreter> already installed but in a non-standard location then you can use the flags
external-stg-interpreter> --extra-include-dirs= and --extra-lib-dirs= to specify where it is.If the
external-stg-interpreter> library file does exist, it may contain errors that are caught by the C
external-stg-interpreter> compiler at the preprocessing stage. In this case you can re-run configure
external-stg-interpreter> with the verbosity flag -v3 to see the error messages.

Try installing libomp from brew and then running:

$ stack run --extra-include-dirs=/usr/local/opt/libomp/include --extra-lib-dirs=/usr/local/opt/libomp/lib

Compile debuggee program with GHC-WPC using stack

• Add the following lines to debuggee's stack.yaml:

  # use custom ext-stg whole program compiler GHC
  compiler:       ghc-9.2.7
  compiler-check: match-exact
  ghc-variant:    wpc
  setup-info:
    ghc:
      linux64-custom-wpc-tinfo6:
        9.2.7:
     	 url: "https://github.com/grin-compiler/foundation-pak/releases/download/ghc-9.2.7/ghc-9.2.7-x86_64-unknown-linux.tar.xz"
      macosx-custom-wpc:
        9.2.7:
     	 url: "https://github.com/grin-compiler/foundation-pak/releases/download/ghc-9.2.7/ghc-9.2.7-x86_64-apple-darwin.tar.xz"
      macosx-aarch64-custom-wpc:
        9.2.7:
     	 url: "https://github.com/grin-compiler/foundation-pak/releases/download/ghc-9.2.7/ghc-9.2.7-aarch64-apple-darwin.tar.xz"

• Run stack build i.e. build the provided sample hello world: (cd sample-program-to-debug ; stack build)

Open debuggee program in VSCode [Extension Development Host]

• Open debugge project folder by using the Files/Open Folder menu.
• Select the debug view on the side bar
• Click to create a launch.json file, then select Haskell DAP ESTGi
• Press F5 or the Play button to start debugging

Development

Allow breakpoints everywhere

Run dap-estgi-extension

Start dap-estgi-server

Compile debuggee program with GHC-WPC using stack

Open debuggee program in VSCode [Extension Development Host]