latex: merge LaTeX packages into a single derivation

Merge the packages used by the chktex, lacheck, and latexindent hooks
into a single pkgs.texlive.combine derivation to reduce installation
size and build time. Only enabled hooks are included in the derivation.

Link: #513

Author: trueNAHO

modules/hooks.nix

@@ -22,6 +22,20 @@ let
     if hook.settings.binPath == null
     then "${hook.package}${binPath}"
     else hook.settings.binPath;
+
+  texliveCombine = pkgs.texlive.combine (
+    lib.mergeAttrsList
+      (
+        map
+          (package: { ${package} = pkgs.texlive.${package}; })
+          (
+            builtins.filter
+              (hook: hooks.${hook}.enable)
+              [ "chktex" "lacheck" "latexindent" ]
+          )
+      )
+    // { inherit (pkgs.texlive) scheme-basic; }
+  );
 in
 {
   imports =
@@ -2228,7 +2242,7 @@ in
           name = "chktex";
           description = "LaTeX semantic checker";
           types = [ "file" "tex" ];
-          package = tools.chktex;
+          package = texliveCombine;
           entry = "${hooks.chktex.package}/bin/chktex";
         };
       clang-format =
@@ -2903,7 +2917,7 @@ lib.escapeShellArgs (lib.concatMap (ext: [ "--ghc-opt" "-X${ext}" ]) hooks.ormol
           name = "latexindent";
           description = "Perl script to add indentation to LaTeX files.";
           types = [ "file" "tex" ];
-          package = tools.latexindent;
+          package = texliveCombine;
           entry = "${hooks.latexindent.package}/bin/latexindent ${hooks.latexindent.settings.flags}";
         };
       lacheck =
@@ -2918,7 +2932,7 @@ lib.escapeShellArgs (lib.concatMap (ext: [ "--ghc-opt" "-X${ext}" ]) hooks.ormol
           name = "lacheck";
           description = "A consistency checker for LaTeX documents.";
           types = [ "file" "tex" ];
-          package = tools.lacheck;
+          package = texliveCombine;
           entry = "${script}";
         };
       lua-ls =

nix/tools.nix

@@ -91,11 +91,6 @@
 }:
 
 
-let
-  tex = texlive.combine {
-    inherit (texlive) latexindent chktex scheme-basic;
-  };
-in
 {
   clang-tools = llvmPackages_latest.clang-tools;
   inherit
@@ -191,11 +186,6 @@ in
   tflint = callPackage ./tflint { };
   dune-build-opam-files = callPackage ./dune-build-opam-files { dune = dune_3; inherit (pkgsBuildBuild) ocaml; };
   dune-fmt = callPackage ./dune-fmt { dune = dune_3; inherit (pkgsBuildBuild) ocaml; };
-  latexindent = tex;
-  lacheck = texlive.combine {
-    inherit (texlive) lacheck scheme-basic;
-  };
-  chktex = tex;
   commitizen = commitizen.overrideAttrs (_: _: { doCheck = false; });
   bats = if bats ? withLibraries then (bats.withLibraries (p: [ p.bats-support p.bats-assert p.bats-file ])) else bats;
   git-annex = if stdenv.isDarwin then null else git-annex;