"nix repl" cannot tab-complete names that contain a dash ('-')

[dtzWill]

The Problem

Consider default.nix:

{
  aaa-bbb = 1;
  aaa-ccc = 2;
}

Pointing nix-repl at this, completions are as follows:

a

nix-repl> a
aaa-bbb  aaa-ccc  abort

aaa-

nix-repl> aaa-
__add                            __findFile                       __langVersion                    __stringLength                   builtins
__addErrorContext                __foldl'                         __length                         __sub                            derivation
__all                            __fromJSON                       __lessThan                       __substring                      derivationStrict
__any                            __functionArgs                   __listToAttrs                    __tail                           dirOf
__attrNames                      __genList                        __match                          __toFile                         false
__attrValues                     __genericClosure                 __mul                            __toJSON                         fetchGit
__catAttrs                       __getAttr                        __nixPath                        __toPath                         fetchMercurial
__compareVersions                __getEnv                         __nixVersion                     __toXML                          fetchTarball
__concatLists                    __hasAttr                        __parseDrvName                   __trace                          import
__concatStringsSep               __hashString                     __partition                      __tryEval                        isNull
__currentSystem                  __head                           __pathExists                     __typeOf                         map
__currentTime                    __intersectAttrs                 __readDir                        __unsafeDiscardOutputDependency  null
__deepSeq                        __isAttrs                        __readFile                       __unsafeDiscardStringContext     placeholder
__div                            __isBool                         __replaceStrings                 __unsafeGetAttrPos               removeAttrs
__elem                           __isFloat                        __seq                            __valueSize                      scopedImport
__elemAt                         __isFunction                     __sort                           aaa-bbb                          throw
__fetchurl                       __isInt                          __split                          aaa-ccc                          toString
__filter                         __isList                         __storeDir                       abort                            true
__filterSource                   __isString                       __storePath                      baseNameOf

Essentially completion here is same as if no input was entered (since linenoise completion callback breaks at dashes on our behalf.)

This is unfortunate (too many suggestions) but not incorrect.

aaa-b

nix-repl> aaa-b
baseNameOf  builtins

This is just wrong :(.

Linenoise, linenoise-ng, readline?

AFAICT this behavior is the same when using linenoise or linenoise-ng, but does not occur in readline-based nix-repl.

Solution?

Not sure if there's an easy answer-- perhaps we can punt on linenoise breaking things for us entirely (instead of teaching it how to kinda parse Nix expressions) and handle this in our completion callback?

I'm not sure what other edge cases might be problematic... I suppose spaces after a "dot" should be ignored...? (readline gets this "wrong" as well)

Anyway it doesn't need to be perfect of course but I think a reasonable goal is to reasonably auto-complete the sorts of expressions/attributes commonly used in nixpkgs.

[jammerful]

@dtzWill Are you talking about nix-repl or nix repl (which is from an unreleased version of nix 1.12). If it is nix-repl the correct repository is here: https://github.com/edolstra/nix-repl

[dtzWill]

nix repl sorry, updated the issue title.

[cumber]

I came here to report this, now that nix 2 has hit unstable, and nix-repl no longer works. Glad to see it's already known.

It's significantly more of a usability problem than I would have expected at first, due to the combination of dashes commonly occurring as word separators in identifiers and big nested collections like emacsPackagesNg.

For example, if I want to find emacs packages related to Haskell it's natural to do:

nix-repl> emacsPackagesNg.haskell<TAB>

At which point the completion engine notices that every possibility continues with a dash, so it fills that in for me, giving me this:

nix-repl> emacsPackagesNg.haskell-<TAB><TAB>
Display all 8666 possibilities? (y or n)

:(

The only way I can see what I want is to delete enough characters so that there are other maatches that don't start with haskell-, which by definition includes other things I was trying to filter out; in this case emacsPackagesNg.hask<TAB><TAB> works, due to the existence of emacsPackagesNg.hasky-extensions, but it's easy to imagine scenarios where the only prefix that also includes things not leading up to the dash also includes an impractically large amount of other stuff.

[dtzWill]

Quick testing shows that https://github.com/dtzWill/nix/tree/fix/nix-repl-hyphen resolves your immediate problem. It's what my quick idea for fixing this was but not sure if it has any negative consequences.

(in particular dtzWill@cd317fb)

[acowley]

dtzWill@cd317fb is such a minor change, and does seem to solve the problem. What is the potential downside of merging it?

[LnL7]

Yeah, this is pretty annoying given that the convention for attribute names seems to be moving towards foo-bar instead of fooBar.

[Skyfold]

I just updated to nix 2.1.3 from nixos-unstable, but still have the issue that any variable names with "-" in them stops all auto-completion (updated with nix-channel --update; nix-env -iA nixpkgs.nix).

The issue is actually much more painful then described because it stops auto-completion of items in a derivation with a "-" in its name. So, pkgs.nodePackages.nodejs-8_x.<tab><tab> returns nothing. The only workaround I have found is to chain lets like this, let t = pkgs.nodejs-8_x in t.<tab><tab> so I can inspect derivations.

[dtzWill]

The recently-merged move to editline (or whichever) addresses this problem! So hopefully in a release or two this'll be fixed by default :). Otherwise you may want to use a copy built from latest master, but it's safer to wait for it to reach a stable release.

…

On Tue, 04 Dec 2018 17:14:10 -0800, Pfalzgraf Martin ***@***.***> wrote: I just updated to nix 2.1.3 from nixos-unstable, but still have the issue that any variable names with "-" in them stops all auto-completion (updated with `nix-channel --update; nix-env -iA nixpkgs.nix`). The issue is actually much more painful then described because it stops auto-completion of items in a derivation with a "-" in its name. So, `pkgs.nodePackages.nodejs-8_x.<tab><tab>` returns nothing. The only workaround I have found is to chain `let`s like this, `let t = pkgs.nodejs-8_x in t.<tab><tab>` so I can inspect derivations. -- You are receiving this because you were mentioned. Reply to this email directly or view it on GitHub: #1756 (comment) part: text/html