diff --git a/.gitignore b/.gitignore
index e94452f..5d97109 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,6 +4,7 @@ lisp-scripts/compile-file-system-p.lisp
 tmp
 bin/asgl
 gecode
+*.cxx
 *.o
 gr1/gr1
 gr1/gr1.c
diff --git a/ecl-1.16.2-libffi-3.3-abi.patch b/ecl-1.16.2-libffi-3.3-abi.patch
new file mode 100644
index 0000000..807687b
--- /dev/null
+++ b/ecl-1.16.2-libffi-3.3-abi.patch
@@ -0,0 +1,15 @@
+diff --git a/src/c/ffi.d b/src/c/ffi.d
+index 8861303e..8a959c23 100644
+--- a/src/c/ffi.d
++++ b/src/c/ffi.d
+@@ -145,8 +145,8 @@ static struct {
+ #elif defined(X86_WIN64)
+         {@':win64', FFI_WIN64},
+ #elif defined(X86_ANY) || defined(X86) || defined(X86_64)
+-        {@':cdecl', FFI_SYSV},
+-        {@':sysv', FFI_SYSV},
++        {@':cdecl', FFI_UNIX64},
++        {@':sysv', FFI_UNIX64},
+         {@':unix64', FFI_UNIX64},
+ #endif
+ };
\ No newline at end of file
diff --git a/ecl-cpp.nix b/ecl-cpp.nix
new file mode 100644
index 0000000..280641f
--- /dev/null
+++ b/ecl-cpp.nix
@@ -0,0 +1,97 @@
+{
+  lib,
+  stdenv,
+  fetchurl,
+  fetchpatch,
+  libtool,
+  autoconf,
+  automake,
+  gmp,
+  mpfr,
+  libffi,
+  makeWrapper,
+  noUnicode ? false,
+  gcc,
+  threadSupport ? false,
+  useBoehmgc ? true,
+  boehmgc,
+}:
+
+assert useBoehmgc -> boehmgc != null;
+
+let
+  s = # Generated upstream information
+    rec {
+      baseName = "ecl";
+      version = "16.1.2";
+      name = "${baseName}-${version}";
+      url = "https://common-lisp.net/project/ecl/static/files/release/ecl-16.1.2.tgz";
+      sha256 = "16ab8qs3awvdxy8xs8jy82v8r04x4wr70l9l2j45vgag18d2nj1d";
+    };
+  buildInputs = [
+    libtool
+    autoconf
+    automake
+    makeWrapper
+  ];
+  propagatedBuildInputs =
+    [
+      libffi
+      gmp
+      mpfr
+      gcc
+    ]
+    ++ lib.optionals useBoehmgc [
+      # replaces ecl's own gc which other packages can depend on, thus propagated
+      boehmgc
+    ];
+in
+stdenv.mkDerivation {
+  inherit (s) name version;
+  inherit buildInputs propagatedBuildInputs;
+
+  src = fetchurl { inherit (s) url sha256; };
+
+  configureFlags = [
+    (if threadSupport then "--enable-threads" else "--disable-threads")
+    "--with-gmp-prefix=${gmp.dev}"
+    "--with-cxx"
+    "--with-libffi-prefix=${libffi.dev}"
+  ] ++ (lib.optional (!noUnicode) "--enable-unicode");
+
+  patches = [
+    (fetchpatch {
+      # Avoid infinite loop, see https://gitlab.com/embeddable-common-lisp/ecl/issues/43 (fixed upstream)
+      name = "avoid-infinite-loop.patch";
+      url = "https://gitlab.com/embeddable-common-lisp/ecl/commit/caba1989f40ef917e7486f41b9cd5c7e3c5c2d79.patch";
+      sha256 = "07vw91psbc9gdn8grql46ra8lq3bgkzg5v480chnbryna4sv6lbb";
+    })
+    (fetchpatch {
+      # Fix getcwd with long pathnames
+      # Rebased version of
+      # https://gitlab.com/embeddable-common-lisp/ecl/commit/ac5f011f57a85a38627af154bc3ee7580e7fecd4.patch
+      name = "getcwd.patch";
+      url = "https://git.sagemath.org/sage.git/plain/build/pkgs/ecl/patches/16.1.2-getcwd.patch?id=07d6c37d18811e2b377a9689790a7c5e24da16ba";
+      sha256 = "1fbi8gn7rv8nqff5mpaijsrch3k3z7qc5cn4h1vl8qrr8xwqlqhb";
+    })
+    ./ecl-1.16.2-libffi-3.3-abi.patch
+  ];
+
+  hardeningDisable = [ "format" ];
+
+  postInstall = ''
+    sed -e 's/@[-a-zA-Z_]*@//g' -i $out/bin/ecl-config
+    wrapProgram "$out/bin/ecl" \
+      --prefix PATH ':' "${gcc}/bin" \
+      --prefix NIX_LDFLAGS ' ' "-L${gmp.lib or gmp.out or gmp}/lib" \
+      --prefix NIX_LDFLAGS ' ' "-L${libffi.lib or libffi.out or libffi}/lib"
+  '';
+
+  meta = {
+    inherit (s) version;
+    description = "Lisp implementation aiming to be small, fast and easy to embed";
+    license = lib.licenses.mit;
+    maintainers = [ lib.maintainers.raskin ];
+    platforms = lib.platforms.unix;
+  };
+}
diff --git a/gecode.nix b/gecode.nix
new file mode 100644
index 0000000..a3c8eec
--- /dev/null
+++ b/gecode.nix
@@ -0,0 +1,48 @@
+{
+  lib,
+  stdenv,
+  fetchurl,
+  fetchpatch,
+  perl,
+}:
+
+stdenv.mkDerivation rec {
+  pname = "gecode";
+  version = "4.3.3";
+
+  src = fetchurl {
+    url = "https://github.com/Gecode/gecode/archive/refs/tags/release-${version}.tar.gz";
+    sha256 = "sha256-EOmQqEtfBH/J4w7wtcFhrVuU7F0NWJO9Qfn4b0QHZaw=";
+  };
+
+  patches = [
+    # (import ./fix-const-weights-clang-patch.nix fetchpatch)
+  ];
+
+  postPatch = ''
+    substituteInPlace gecode/flatzinc/lexer.yy.cpp \
+      --replace "register " ""
+  '';
+
+  nativeBuildInputs = [ perl ];
+
+  preConfigure = "patchShebangs configure";
+
+  configureFlags = [
+    "--disable-gist"
+    "--disable-qt"
+    "--disable-examples"
+    "--disable-flatzinc"
+    "--disable-float-vars"
+  ];
+
+  env.CXXFLAGS = lib.optionalString stdenv.cc.isClang "-std=c++14";
+
+  meta = with lib; {
+    license = licenses.mit;
+    homepage = "https://www.gecode.org";
+    description = "Toolkit for developing constraint-based systems";
+    platforms = platforms.all;
+    maintainers = [ maintainers.manveru ];
+  };
+}
diff --git a/gemset.nix b/gemset.nix
new file mode 100644
index 0000000..738180f
--- /dev/null
+++ b/gemset.nix
@@ -0,0 +1,117 @@
+{
+  aruba = {
+    dependencies = ["childprocess" "cucumber" "rspec-expectations"];
+    groups = ["default"];
+    platforms = [];
+    source = {
+      remotes = ["https://rubygems.org"];
+      sha256 = "0hlq03shd7cl72n7nark8dm5gdrsjpcqkxd2qrkcjzd35nkqqlbw";
+      type = "gem";
+    };
+    version = "0.6.2";
+  };
+  builder = {
+    groups = ["default"];
+    platforms = [];
+    source = {
+      remotes = ["https://rubygems.org"];
+      sha256 = "14fii7ab8qszrvsvhz6z2z3i4dw0h41a62fjr2h1j8m41vbrmyv2";
+      type = "gem";
+    };
+    version = "3.2.2";
+  };
+  childprocess = {
+    dependencies = ["ffi"];
+    groups = ["default"];
+    platforms = [];
+    source = {
+      remotes = ["https://rubygems.org"];
+      sha256 = "0cxzh17vjlmpqfcas4815x50dc1gzfwgbs51zzpd4chrl6ak4n4v";
+      type = "gem";
+    };
+    version = "0.5.5";
+  };
+  cucumber = {
+    dependencies = ["builder" "diff-lcs" "gherkin" "multi_json" "multi_test"];
+    groups = ["default"];
+    platforms = [];
+    source = {
+      remotes = ["https://rubygems.org"];
+      sha256 = "170a0yclrc1i9m5wjgwzga3ipb5mbapiha8jcg0g2gjnmzvd77nr";
+      type = "gem";
+    };
+    version = "1.3.19";
+  };
+  diff-lcs = {
+    groups = ["default"];
+    platforms = [];
+    source = {
+      remotes = ["https://rubygems.org"];
+      sha256 = "1vf9civd41bnqi6brr5d9jifdw73j9khc6fkhfl1f8r9cpkdvlx1";
+      type = "gem";
+    };
+    version = "1.2.5";
+  };
+  ffi = {
+    groups = ["default"];
+    platforms = [];
+    source = {
+      remotes = ["https://rubygems.org"];
+      sha256 = "0ph098bv92rn5wl6rn2hwb4ng24v4187sz8pa0bpi9jfh50im879";
+      type = "gem";
+    };
+    version = "1.9.8";
+  };
+  gherkin = {
+    dependencies = ["multi_json"];
+    groups = ["default"];
+    platforms = [];
+    source = {
+      remotes = ["https://rubygems.org"];
+      sha256 = "1mxfgw15pii1jmq00xxbyp77v71mh3bp99ndgwzfwkxvbcisha25";
+      type = "gem";
+    };
+    version = "2.12.2";
+  };
+  multi_json = {
+    groups = ["default"];
+    platforms = [];
+    source = {
+      remotes = ["https://rubygems.org"];
+      sha256 = "1mg3hp17ch8bkf3ndj40s50yjs0vrqbfh3aq5r02jkpjkh23wgxl";
+      type = "gem";
+    };
+    version = "1.11.0";
+  };
+  multi_test = {
+    groups = ["default"];
+    platforms = [];
+    source = {
+      remotes = ["https://rubygems.org"];
+      sha256 = "1sx356q81plr67hg16jfwz9hcqvnk03bd9n75pmdw8pfxjfy1yxd";
+      type = "gem";
+    };
+    version = "0.1.2";
+  };
+  rspec-expectations = {
+    dependencies = ["diff-lcs" "rspec-support"];
+    groups = ["default"];
+    platforms = [];
+    source = {
+      remotes = ["https://rubygems.org"];
+      sha256 = "08ba5hprb3kf849yylkxm9dd9lfazh7gapiqxy5lapwqxbqpa3ky";
+      type = "gem";
+    };
+    version = "3.2.0";
+  };
+  rspec-support = {
+    groups = ["default"];
+    platforms = [];
+    source = {
+      remotes = ["https://rubygems.org"];
+      sha256 = "194zry5195ls2hni7r9824vqb5d3qfg4jb15fgj8glfy0rvw3zxl";
+      type = "gem";
+    };
+    version = "3.2.2";
+  };
+}
diff --git a/nix-build.sh b/nix-build.sh
new file mode 100755
index 0000000..f90b6a3
--- /dev/null
+++ b/nix-build.sh
@@ -0,0 +1,11 @@
+#!/bin/bash
+
+set -euxo pipefail
+
+# git add .
+# git commit -m wip || true
+
+git clean -fxd
+
+nix-shell \
+    --pure --run 'bash steps.sh'
diff --git a/nix-test.sh b/nix-test.sh
new file mode 100755
index 0000000..92f41d3
--- /dev/null
+++ b/nix-test.sh
@@ -0,0 +1,8 @@
+#!/bin/bash
+
+set -euxo pipefail
+
+make data/iccma15_solutions data/iccma15_testcases
+
+nix-shell \
+    --pure --run 'ASGL_HOME=`pwd` make test'
diff --git a/shell.nix b/shell.nix
new file mode 100644
index 0000000..0ccda03
--- /dev/null
+++ b/shell.nix
@@ -0,0 +1,31 @@
+{
+  pkgs ? import <nixpkgs> { },
+}:
+
+let
+  ecl_cpp = pkgs.callPackage ./ecl-cpp.nix { };
+  gecode = pkgs.callPackage ./gecode.nix { };
+  cucumber-aruba-from-gemfile = pkgs.bundlerEnv {
+    name = "cucumber-aruba-for-asgl";
+    inherit (pkgs.ruby);
+    gemdir = ./.;
+  };
+in
+
+pkgs.mkShell {
+  buildInputs = [
+    pkgs.which
+    # For building
+    pkgs.autoconf
+    ecl_cpp
+    gecode
+    pkgs.ragel
+    # For tests
+    cucumber-aruba-from-gemfile
+    pkgs.ruby
+    pkgs.perl
+  ];
+  shellHook = ''
+    echo "Welcome to the development environment!"
+  '';
+}
diff --git a/steps.sh b/steps.sh
new file mode 100644
index 0000000..1a2b5ec
--- /dev/null
+++ b/steps.sh
@@ -0,0 +1,14 @@
+set -euxo pipefail
+
+echo hello
+
+autoconf configure.ac > configure
+chmod +x configure
+
+./configure --without-gist
+
+./scripts/generate-make-mk.sh
+
+make
+
+./bin/asgl