In reply to @b:chreekat.net
DRY is in frequent conflict with YAGNI

DRY: don't write the same thing twice
YAGNI: don't define something you don't (yet) need

I can see how they conflict when applied loosely, but applying DRY carefully should be OK.

Maybe something like this?

lens_5_3_3 = self.callHackageDirect {
  pkg = "HaskellNet-SSL";
  ver = "5.3.3";
  sha256 = "sha256-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=";
} {};

Maybe something like this?

lens_5_3_3 = self.callHackageDirect {
  pkg = "lens";
  ver = "5.3.3";
  sha256 = "sha256-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=";
} {};

Maybe something like this?

lens_5_3_3 = callHackageDirect {
  pkg = "lens";
  ver = "5.3.3";
  sha256 = "sha256-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=";
} {};

Maybe something like this?

lens_5_3_3 = pkgs.haskell.lib.callHackageDirect {
  pkg = "lens";
  ver = "5.3.3";
  sha256 = "sha256-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=";
} {};

pkgs.haskellPackages.lens.overrideAttrs {
  version = "5.3.3";
  src = pkgs.fetchzip {
     url = "mirror://hackage/lens-5.3.3/lens-5.3.3.tar.gz";
     hash = "sha256-3xm0+HH2CY3rcigl8x1kYVLOW5PVFhilg0s0hxHxzWE=";
  };
};

In reply to @implicit_operative:matrix.org

Maybe something like this?

lens_5_3_3 = pkgs.haskell.lib.callHackageDirect {
  pkg = "lens";
  ver = "5.3.3";
  sha256 = "sha256-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=";
} {};

In reply to @b:chreekat.net
They're fundamentally in conflict. You only avoid conflict precisely by applying them loosely. :) DRY, applied religiously, requires you to define abstractions very early that allow slightly different use cases to share common expressions. But abstractions have a cost. Copy/paste/modify is often cheaper. And most importantly, it requires a lot less careful thought. Wasting brainpower to develop a thoughtful abstraction for something that will never have more than two use cases is a shame. That's really the essence of YAGNI.