Generate separate manpages for each nix subcommand

doc/manual/generate-manpage.nix

@@ -1,34 +1,40 @@
+command:
+
 with builtins;
 with import ./utils.nix;
 
 let
 
   showCommand =
-    { command, section, def }:
-    "${section} Name\n\n"
+    { command, def, filename }:
+    "# Name\n\n"
     + "`${command}` - ${def.description}\n\n"
-    + "${section} Synopsis\n\n"
+    + "# Synopsis\n\n"
     + showSynopsis { inherit command; args = def.args; }
+    + (if def.commands or {} != {}
+       then
+         "where *subcommand* is one of the following:\n\n"
+         # FIXME: group by category
+         + concatStrings (map (name:
+           "* [`${command} ${name}`](./${appendName filename name}.md) - ${def.commands.${name}.description}\n")
+           (attrNames def.commands))
+         + "\n"
+       else "")
     + (if def ? doc
-       then "${section} Description\n\n" + def.doc + "\n\n"
+       then "# Description\n\n" + def.doc + "\n\n"
        else "")
     + (let s = showFlags def.flags; in
        if s != ""
-       then "${section} Flags\n\n${s}"
+       then "# Flags\n\n${s}"
        else "")
     + (if def.examples or [] != []
        then
-         "${section} Examples\n\n"
+         "# Examples\n\n"
          + concatStrings (map ({ description, command }: "${description}\n\n```console\n${command}\n```\n\n") def.examples)
-       else "")
-    + (if def.commands or [] != []
-       then concatStrings (
-         map (name:
-           "# Subcommand `${command} ${name}`\n\n"
-           + showCommand { command = command + " " + name; section = "##"; def = def.commands.${name}; })
-           (attrNames def.commands))
        else "");
 
+  appendName = filename: name: (if filename == "nix" then "nix3" else filename) + "-" + name;
+
   showFlags = flags:
     concatStrings
       (map (longName:
@@ -48,8 +54,20 @@ let
     "`${command}` [*flags*...] ${concatStringsSep " "
       (map (arg: "*${arg.label}*" + (if arg ? arity then "" else "...")) args)}\n\n";
 
+  processCommand = { command, def, filename }:
+    [ { name = filename + ".md"; value = showCommand { inherit command def filename; }; inherit command; } ]
+    ++ concatMap
+      (name: processCommand {
+        filename = appendName filename name;
+        command = command + " " + name;
+        def = def.commands.${name};
+      })
+      (attrNames def.commands or {});
+
 in
 
-command:
-
-showCommand { command = "nix"; section = "#"; def = command; }
+let
+  manpages = processCommand { filename = "nix"; command = "nix"; def = command; };
+  summary = concatStrings (map (manpage: "    - [${manpage.command}](command-ref/new-cli/${manpage.name})\n") manpages);
+in
+(listToAttrs manpages) // { "SUMMARY.md" = summary; }