error in flake.

[stepa1000]

I copy flake with nix flake init --template templates#haskell-nix --impure,
but when i run nix develop
I get:

warning: Git tree '/home/stepan/Documents/GitHub/Axon-space-hs' is dirty
warning: ignoring untrusted substituter 'https://cache.iog.io', you are not a trusted user.
Run `man nix.conf` for more information on the `substituters` configuration option.
warning: ignoring the client-specified setting 'trusted-public-keys', because it is a restricted setting and you are not a trusted user
evaluation warning: Nixpkgs 26.05 will be the last release to support x86_64-darwin; see https://nixos.org/manual/nixpkgs/unstable/release-notes#x86_64-darwin-26.05
trace: WARNING: `cleanSourceWith` called on /nix/store/qwvgspf2adgklgdbb193fsila1dz9km5-source without a `name`. Consider adding `name = "qwvgspf2adgklgdbb193fsila1dz9km5-source";`
error:
       … while evaluating the attribute 'packages'
         at /nix/store/qwvgspf2adgklgdbb193fsila1dz9km5-source/flake.nix:42:9:
           41|
           42|         packages = flake.packages // { default = flake.packages."Axon-space-hs:exe:Axon-space-hs-exe"; };
             |         ^
           43|       });

       … in the left operand of the update (//) operator
         at /nix/store/qwvgspf2adgklgdbb193fsila1dz9km5-source/flake.nix:42:35:
           41|
           42|         packages = flake.packages // { default = flake.packages."Axon-space-hs:exe:Axon-space-hs-exe"; };
             |                                   ^
           43|       });

       (stack trace truncated; use '--show-trace' to show the full, detailed trace)

       error: Cannot build '/nix/store/ys74y35ihxcrjlcl6phw8m1lgxvi0q09-stack-repos.drv'.
       Reason: builder failed with exit code 1.
       Output paths:
         /nix/store/k9pslgmk7c27icay8xxyg66w64sdpl5p-stack-repos
       Last 5 log lines:
       > substituteStream() in derivation stack-repos: WARNING: '--replace' is deprecated, use --replace-{fail,warn,quiet}. (file 'stack.yaml')
       > substituteStream() in derivation stack-repos: WARNING: pattern \#\ nix-sha256: doesn't match anything in file 'stack.yaml'
       > stack-repos: AesonException "Error in $: key \"resolver\" not found"
       > CallStack (from HasCallStack):
       >   error, called at lib/StackRepos.hs:36:15 in nix-tools-0.1.0.0-Hsb4lIKiGVOCO64PwH8LnT:StackRepos
       For full logs, run:
         nix log /nix/store/ys74y35ihxcrjlcl6phw8m1lgxvi0q09-stack-repos.drv

I modify flake.nix, now is:

 {
  # This is a template created by `hix init`
  inputs.haskellNix.url = "github:input-output-hk/haskell.nix";
  inputs.nixpkgs.follows = "haskellNix/nixpkgs-unstable";
  inputs.flake-utils.url = "github:numtide/flake-utils";
  outputs = { self, nixpkgs, flake-utils, haskellNix }:
    let
      supportedSystems = [
        "x86_64-linux"
        "x86_64-darwin"
      ];
    in
      flake-utils.lib.eachSystem supportedSystems (system:
      let
        overlays = [ haskellNix.overlay
          (final: prev: {
            hixProject =
              final.haskell-nix.hix.project {
                src = ./.;
                evalSystem = "x86_64-linux";
		shell.tools = {
		  stack = {};
		  };
	        shell.buildInputs = with pkgs; [
                  zlib # Example of a C library dependency
                  OpenGL
                  freeglut
                  gl
	          GLUT
	          GLUtil
                  libGL
                  libGLU
		  ];
              };
          })
        ];
        pkgs = import nixpkgs { inherit system overlays; inherit (haskellNix) config; };
        flake = pkgs.hixProject.flake {};
      in flake // {
        legacyPackages = pkgs;

        packages = flake.packages // { default = flake.packages."Axon-space-hs:exe:Axon-space-hs-exe"; };
      });

  # --- Flake Local Nix Configuration ----------------------------
  nixConfig = {
    # This sets the flake to use the IOG nix cache.
    # Nix should ask for permission before using it,
    # but remove it here if you do not want it to.
    extra-substituters = ["https://cache.iog.io"];
    extra-trusted-public-keys = ["hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ="];
    allow-import-from-derivation = "true";
  };
}

[stepa1000]

when i make pure exemple from nix flake init --template templates#haskell-nix --impure i stuck when [16/1/211 built] building hpke-0.1.0.tar.gz: Dload Upload Total Spent Left Speed

[stepa1000]

[16/1/211 built] building hpke-0.1.0.tar.gz: Warning: Problem (retrying all errors). Will retry in 1 second. 3 retries left.

[hamishmack]

The key error here is:

stack-repos: AesonException "Error in $: key "resolver" not found"

Your project directory contains a stack.yaml, so haskell.nix processed it as a Stack project. The problem: Stack 2.15.1 renamed the top-level resolver: key to snapshot: (both are accepted by Stack, and stack new now emits snapshot:), but haskell.nix's stack.yaml parser only recognised resolver:. So a snapshot:-only stack.yaml blew up with key "resolver" not found.

Fix: #2532 makes haskell.nix accept snapshot: as a synonym for resolver: (both in the nix-tools parser and in lib/fetch-resolver.nix). Verified stack-repos now handles a snapshot: lts-XX stack.yaml.

Immediate workarounds until that lands:

• Rename snapshot: to resolver: in your stack.yaml (they're synonyms), or
• If you don't actually want a Stack build (the template is Cabal-based), remove the stack.yaml so haskell.nix uses your .cabal/cabal.project.

Two side notes:

• The [16/1/211] building hpke-0.1.0.tar.gz … retrying you saw with the pristine template is a transient network hiccup fetching from Hackage, not a haskell.nix bug — with the binary cache configured (or on retry) it goes through.
• Separately, the old templates#haskell-nix template pinned an unsupported GHC (ghc926); that's fixed in templates: host the getting-started scaffold in-repo (fixes #2518) #2531 / haskell.nix: bump template GHC ghc926 -> ghc96 NixOS/templates#101. The getting-started template now uses a supported GHC.