[Nix-dev] yet another npm2nix reengineering attempt

[Sander van der Burg]

It's stateful because the packages that end up in a dependency's
node_modules/ folder depend on the packages that have been stored in any of
the includer's (parent directory's) node_modules/ folders. When a
dependency has been encountered a second time (that fits within a package's
version range), NPM will not include it again.

For example: if a package would declare a dependency (such as: "optparse":
">= 1.0.3") and any of the parent node_modules/ folders would provide
version 1.0.5, then optparse/ will not be deployed again in the package's
private node_modules/ folder. Instead, it will be left out and the package
binds to the version of the parent.

Second, with npm 3.x's flat module installations, we must move packages as
high as possible in the nested node_modules/ hierarchy, until a conflict
has been encountered.

On Tue, Mar 1, 2016 at 1:53 PM, Shea Levy <shea at shealevy.com> wrote:

> "including NPM dependencies is stateful" how so? Having separate
> derivations symlinked in would give you sharing, no?
>
> On 2016-03-01 08:15, Sander van der Burg wrote:
> > Hi,
> >
> > I don't know how many of you have noticed my latest blog post
> >
> > (
> http://sandervanderburg.blogspot.com/2016/02/managing-npm-flat-module-installations.html
> > [1]), but I did yet another reengineering attempt for npm2nix. Its
> > main objective is to also support npm 3.x's flat module installations
> > (npm 3.x comes with Node.js 5.x).
> >
> > In the second reengineered version, I compute the entire dependency
> > graph ahead of time and build the entire set of dependencies in one
> > derivation -- there is no good reason to make them individual Nix
> > packages, because including NPM dependencies is stateful.
> >
> > The new reengineered version supports both Node.js 4.x and 5.x. By
> > default, it generates expressions for 4.x (I made this the default,
> > since 4.x is the LTS release):
> >
> > $ npm2nix
> >
> > Adding the -5 parameter causes it to generate expressions for Node.js
> > 5.x:
> >
> > $ npm2nix -5
> >
> > The code lives in the same repository as the old reengineering
> > version, but in a different branch:
> >
> > https://github.com/svanderburg/npm2nix/tree/reengineering2 [2]
> >
> > There is a README.md file that describes how to use it and
> > demonstrates a few common use cases.
> >
> > The flat module installation works for many of my packages but it is
> > still not 100% perfect. My blog post describes some of its
> > limitations.
> >
> > Anyway, I'm announcing this new version so that I can gather
> > feedback. Maybe this new implementation is not what people are
> > actually looking for, but I'm eating my own dogfood with it now and
> > for all my own projects it works fine.
> >
> > Regards,
> >
> > Sander
> >
> >
> >
> > Links:
> > ------
> > [1]
> >
> >
> http://sandervanderburg.blogspot.com/2016/02/managing-npm-flat-module-installations.html
> > [2] https://github.com/svanderburg/npm2nix/tree/reengineering2
> >
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