add NixEdit command to naviage nixpkgs by attribute name

plugin/nix.vim

@@ -0,0 +1,23 @@
+function! nix#find_drv_position()
+  let line = search("description")
+  if line == 0
+    let line = search("name")
+  endif
+  if line == 0
+    echo "error: could not find derivation"
+    return
+  endif
+
+  return expand("%") . ":" . line
+endfunction
+
+function! nix#edit(attr)
+  let output = system("nix-instantiate --eval ./. -A " . a:attr . ".meta.position")
+  if match(output, "^error:") == -1
+    let position = split(split(output, '"')[0], ":")
+    execute "edit " . position[0]
+    execute position[1]
+  endif
+endfunction
+
+command! -bang -nargs=* NixEdit call nix#edit(<q-args>)