From c257c2adc42543a856b13d75258b4c8c1ee7512f Mon Sep 17 00:00:00 2001
From: Jannik Donker <me@jannikdonker.de>
Date: Fri, 10 Jul 2026 07:56:15 +0200
Subject: [PATCH] more debugging stuff

---
 lua/debugging.lua | 52 ++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 49 insertions(+), 3 deletions(-)

diff --git a/lua/debugging.lua b/lua/debugging.lua
index ef5c5c6..8a2097d 100644
--- a/lua/debugging.lua
+++ b/lua/debugging.lua
@@ -2,11 +2,14 @@ local dap, dapui = require("dap"), require("dapui")
 
 -- Install debug adapters via Mason (same pattern as the LSP tool loop in
 -- plugins.lua). codelldb -> c/cpp/rust, debugpy -> python,
--- js-debug-adapter -> node/ts. java-debug-adapter is installed by the LSP
--- ensure loop and wired through jdtls (see lua/lsp.lua).
+-- js-debug-adapter -> node/ts, haskell-debug-adapter -> haskell.
+-- java-debug-adapter is installed by the LSP ensure loop and wired through
+-- jdtls (see lua/lsp.lua).
+-- Note: haskell-debug-adapter builds from source via cabal on first install
+-- (needs ghc/cabal on PATH) so it can take a few minutes to appear.
 local registry = require("mason-registry")
 registry.refresh(function()
-    for _, tool in ipairs({ "debugpy", "codelldb", "js-debug-adapter" }) do
+    for _, tool in ipairs({ "debugpy", "codelldb", "js-debug-adapter", "haskell-debug-adapter" }) do
         local ok, pkg = pcall(registry.get_package, tool)
         if ok and not pkg:is_installed() then pkg:install() end
     end
@@ -60,6 +63,49 @@ for _, ft in ipairs({ "javascript", "typescript" }) do
     }
 end
 
+-- Haskell (plain ghc): mason-nvim-dap's default handler auto-wires the
+-- haskell-debug-adapter, but its default launch config assumes `stack ghci`
+-- (with a literal "TARGET" placeholder). Override it to drive ghci-dap
+-- directly so a bare `.hs` file debugs with <F5> — no cabal/stack project
+-- required. ghci-dap resolves via PATH (mason bin). Switch ghciCmd to
+-- `cabal exec -- ghci-dap ...` or `stack ghci --with-ghc=ghci-dap ...` if you
+-- later move to a build tool. Verified end-to-end: loads ${file}, stops at
+-- entry, hits breakpoints.
+dap.configurations.haskell = {
+    {
+        type = "haskell",
+        request = "launch",
+        name = "Debug (ghc)",
+        workspace = "${workspaceFolder}",
+        startup = "${file}",
+        stopOnEntry = true,
+        logFile = vim.fs.joinpath(vim.fn.stdpath("data"), "haskell-dap.log"),
+        logLevel = "WARNING",
+        ghciEnv = vim.empty_dict(),
+        ghciPrompt = "H>>= ",
+        ghciInitialPrompt = "ghci> ",
+        ghciCmd = "ghci-dap --interactive -i${workspaceFolder} ${startup}",
+    },
+}
+
+-- Run debuggees in dap-ui's Console terminal so programs that read user input
+-- work. Without this, nvim-dap uses an output-only internal console with no
+-- stdin (the program just hangs on input()/getLine/scanf). dap-ui registers its
+-- Console as dap.defaults.fallback.terminal_win_cmd, so any adapter that runs
+-- the program in an integrated terminal is routed there. Adapters disagree on
+-- the key -- debugpy/pwa-node use `console`, codelldb uses `terminal` -- and
+-- each ignores the other, so set both on every launch config. Applies to the
+-- mason-auto-generated configs (python/cpp/rust) too, since it runs after their
+-- setup. To type: focus the Console window and press `i` (terminal insert).
+for _, configs in pairs(dap.configurations) do
+    for _, cfg in ipairs(configs) do
+        if cfg.request == "launch" then
+            if cfg.console == nil then cfg.console = "integratedTerminal" end
+            if cfg.terminal == nil then cfg.terminal = "integrated" end
+        end
+    end
+end
+
 -- Open/close the dap-ui panels automatically with the session.
 dap.listeners.before.attach.dapui_config           = function() dapui.open() end
 dap.listeners.before.launch.dapui_config           = function() dapui.open() end