| 2 Mar 2026 |
 Alex | For reproducibility, I should also mention this:
alex@alex-pc3 ~> nixos-version
25.11.2793.89dbf01df72e (Xantusia)
| 21:28:03 |
| Alex | * Works fine for me.
alex@alex-pc3 ~> nix-shell -p ghc --run fish
alex@alex-pc3 nix-shell:/t/nix-shell-1930075-2124826253> ghc -prof Hello.hs
[1 of 2] Compiling Main ( Hello.hs, Hello.o )
[2 of 2] Linking Hello
alex@alex-pc3 nix-shell:/t/nix-shell-1930075-2124826253> ./Hello +RTS -p
Hello, world!
alex@alex-pc3 nix-shell:/t/nix-shell-1930075-2124826253> cat Hello.prof
Mon Mar 2 21:25 2026 Time and Allocation Profiling Report (Final)
Hello +RTS -p -RTS
total time = 0.00 secs (0 ticks @ 1000 us, 1 processor)
total alloc = 49,280 bytes (excludes profiling overheads)
COST CENTRE MODULE SRC %time %alloc
MAIN MAIN <built-in> 0.0 22.7
CAF GHC.Internal.IO.Handle.FD <entire-module> 0.0 70.5
CAF GHC.Internal.IO.Encoding <entire-module> 0.0 5.0
CAF GHC.Internal.Conc.Signal <entire-module> 0.0 1.3
individual inherited
COST CENTRE MODULE SRC no. entries %time %alloc %time %alloc
MAIN MAIN <built-in> 138 0 0.0 22.7 0.0 100.0
CAF GHC.Internal.Conc.Signal <entire-module> 262 0 0.0 1.3 0.0 1.3
CAF GHC.Internal.IO.Encoding <entire-module> 208 0 0.0 5.0 0.0 5.0
CAF GHC.Internal.IO.Encoding.Iconv <entire-module> 206 0 0.0 0.4 0.0 0.4
CAF GHC.Internal.IO.Handle.FD <entire-module> 197 0 0.0 70.5 0.0 70.5
CAF Main <entire-module> 145 0 0.0 0.1 0.0 0.1
| 21:29:28 |
| 3 Mar 2026 |
 iclanzan | I figured it out. I am using TemplateHaskell and for that to work with -prof I needed to add -fexternal-interpreter. GHC’s error message indicated that as a possible solution but I didn’t explore it. 🤦 | 01:34:03 |
| 4 Mar 2026 |
 sterni | in this case updating should help recent versions of nixpkgs build cabal2nix against Cabal 3.14 | 21:21:58 |
| 5 Mar 2026 |
|  @kintrix:matrix.org left the room. | 17:13:04 |
| 6 Mar 2026 |
|  nki ⚡️⚡️ changed their display name from nki ⚡️ to nki ⚡️⚡️. | 18:41:12 |
| 8 Mar 2026 |
|  Jack (he/him) changed their display name from Jack to Jack (he/him). | 07:37:36 |
 ncfavier | I have a strange situation where building a Haskell package on aarch64-darwin results in more references than expected (as reported by nix-store -q --references), and most of them are not actually present in the output (at least grep -ra doesn't find them). Does this ring a bell for anyone? To reproduce, clone https://github.com/the1lab/1lab and run nix-build -A shakefile. | 15:48:14 |
| Alex | I recall hearing of a much alike issue before.
Have you looked at the output of nix why-depends --all --precise? | 15:52:37 |
| ncfavier | Thanks, that helped me figure out that the references are through symbolic links, which grep doesn't follow by default. | 16:01:40 |
| 9 Mar 2026 |
| sterni | I finally discovered what breaks HLS on 9.12.3 and its a bug that has been present in Cabal 3.14 all along, but was masked by a bug that has been fixed in Cabal 3.14.2.0 lol https://github.com/haskell/cabal/issues/11598 | 15:03:54 |
| sterni |
- https://github.com/fourmolu/fourmolu/pull/518
- https://github.com/Bodigrim/cabal-add/pull/10
| 15:22:44 |
| sterni | IMO a bad change, though, since it doesn't make sense that build-tool-depends are available at test suite run time. Cabal should have rather added a different mechanism (that has been needed since forever) for this. | 15:23:50 |
 chreekat | You typoed the name of the executable on the report to cabal-add :P (you wrote fourmolu) | 16:11:15 |
 alexfmpe | Oh yay more build-tool-depends annoyances | 18:13:04 |
| alexfmpe | https://github.com/well-typed/haskell-debugger/pull/203 | 18:13:07 |
| alexfmpe | Which quickly got reverted because cabal somehow failed to build cabal | 18:15:21 |
| alexfmpe | https://github.com/well-typed/haskell-debugger/issues/206 | 18:16:06 |
| alexfmpe | * Oh yay more build-tool-depends annoyances. I recently ran into | 18:16:34 |
| 10 Mar 2026 |
| sterni | chreekat: well it's forever now… | 10:00:30 |
|  prescientmoon changed their profile picture. | 11:07:59 |
| 11 Mar 2026 |
|  itamar joined the room. | 00:38:04 |
| alexfmpe | I'm truly confused...
https://github.com/NixOS/nixpkgs/commit/34f316a97a3e0e69bea9b44cd1142f7e73557437 broke haskell.packages.ghc914.haskell-debugger - reverting the commit fixes it
the reason is that the older hie-bios's bounds do not build with 9.14 boot libs
however, switching back to recent hie-bios in configuration-9.14.nix causes failures in the test suite when building hie-bios???
oddly enough, the older hie-bios does build with jailbreak | 14:52:55 |
| alexfmpe | * I'm truly confused...
https://github.com/NixOS/nixpkgs/commit/34f316a97a3e0e69bea9b44cd1142f7e73557437 broke haskell.packages.ghc914.haskell-debugger - reverting the commit fixes it
the reason is that the older hie-bios's bounds do not build with 9.14 boot libs
however, switching back to recent hie-bios in configuration-9.14.nix causes failures in the test suite when building hie-bios???
the older hie-bios does build with jailbreak, doesn't seem like much changed for 9.14: https://github.com/haskell/hie-bios/commits/master/ | 14:53:23 |
| sterni | alexfmpe: you probably lose an override that is otherwise applied to hie-bios | 19:06:52 |
| sterni | the order of the overlays matters and it is not always ideal | 19:07:13 |
| alexfmpe | Aaaah yeah could be, I PR'd jailbreak for now since it works | 19:12:42 |
| 12 Mar 2026 |
| sterni | alexfpe: https://hydra.nixos.org/build/323993958 | 20:35:21 |
| sterni | * alexfmpe: https://hydra.nixos.org/build/323993958 | 20:35:26 |
| sterni | alexfmpe: probably a regression from 9.12.2 -> 9.12.3, curious | 21:47:51 |
