In reply to@infinisil:matrix.org
Cathal OGrady: pkgs.mkShellNoCC should do it mostly

hi, folks
what's wrong with this trivial example

 let
  # factorial : int —> int
  factorial = n: if n == 0 then 1
                           else n * factorial (n — 1);
 in
  factorial 5

results in error

[Running: nix-instantiate --eval play.nix]
error: syntax error, unexpected invalid token, expecting ')'

       at /home/play.nix:4:49:

            3|   factorial = n: if n == 0 then 1
            4|                            else n * factorial (n — 1);
             |                                                 ^
            5|  in
[Command exited with 1]

In reply to @aloisw:kde.org
I don't think Nix supports all of these weird Unicode characters you have around the "minus" sign (that's an em dash to begin with).

oh, ok, thx, that's some artifact of copy-paste from a browser page, some strange non-space whitespace and em dash instead of hyphen

Hi folks, how to default to latest version of package if version is not passed, something like this:

openssl = { version }: pkgs.openssl.overrideAttrs (final: prev: {
  if version {
    src = {
      rev = "${version}";
};
});

Hi folks, how to default to latest version of package if version is not passed, something like this:

openssl = { version }: pkgs.openssl.overrideAttrs (final: prev: {
  if version {
    src = {
      rev = "${version}";
};
});

Ah:

          src = if version != "" then pkgs.fetchurl {
            url = "https://www.openssl.org/source/openssl-${version}.tar.gz";
            hash = hash;
          } else
          prev.src;

does the job.