lowdown 1.4.0 changed the lowdown_opts to include a new and separate
lowdown_opts_term which allows for configuring values specific to
-Tterm (which we're using). This version should have been called 2.0.0
according to semver, hence 2.0.0 was released later without any actual
breaking changes to sort of migitate the problem.
We need to support lowdown >= 1.3 && < 1.4 since the ship has sailed for
updating lowdown in NixOS 25.05 as well as lowdown >= 1.4 or we'll be
stuck in Nixpkgs forever. Support for < 1.4 can be dropped as soon as
NixOS 25.05 is EOL, assuming this change lands before NixOS 25.11
branch-off.
We detect the changed API based on the lowdown version from pkg-config
and define LOWDOWN_SEPARATE_TERM_OPTS based on that. The ifdef is named
according to the specific API change that impacts us, so that it's
hopefully a little simpler to maintain going forward. In the new API,
all newly configurable settings use what would have been the (implicit)
default before. Changing some of these values, especially hpadding,
could be interesting in future changes.
Compared to cl/3081, this change makes sure to initialize all new fields
of lowdown_opts_term explicitly.
It seems that, while making -Tterm more configurable, lowdown's word
wrapping behavior changed slightly which broke basic_repl.test. I've
chosen to work around this by using builtins.add as an example which has
a very short documentation string, so wrapping doesn't matter.
Change-Id: Id73be4c0e43d7eb4f56e10a261b4254402698ff8
This is a really old test case (which was originally written before the
proper Nix syntax). The tested deep comparison behavior was implemented
and reverted soon after due to performance problems, but it has been
restored in today's Nix again (thanks to the derivation comparison
optimization, presumably).
* Clarify the documentation of foldl': That the arguments are forced
before application (?) of `op` is necessarily true. What is important
to stress is that we force every application of `op`, even when the
value turns out to be unused.
* Move the example before the comment about strictness to make it less
confusing: It is a general example and doesn't really showcase anything
about foldl' strictness.
* Add test cases which nail down aspects of foldl' strictness:
* The initial accumulator value is not forced unconditionally.
* Applications of op are forced.
* The list elements are not forced unconditionally.
sternenseemann