NixOS Module System

Sender	Message	Time
16 May 2025
h7x4	I believe the attrs are merged before being typechecked. I suppose you could try adding a `lib.trace` inside the typecheck to verify?	20:32:31
SomeoneSerge (UTC+U[-12,12])	`trace: { below = "_"; } trace: { marker_b = "bar"; } trace: { above = "_"; } trace: { below = "_"; } { foo = { above = "_"; below = "_"; marker_b = "bar"; }; }` For modules: `{ foo = { above = "_"; }; } { foo.marker_b = "bar"; } { foo = { below = "_"; }; }`	20:37:22
SomeoneSerge (UTC+U[-12,12])	* `trace: { below = "_"; } trace: { marker_b = "bar"; } trace: { above = "_"; } trace: { below = "_"; } { foo = { above = "_"; below = "_"; marker_b = "bar"; }; }` For modules: `{ foo = { above = "_"; }; } { foo.marker_b = "bar"; } { foo = { below = "_"; }; }`	20:37:32
Matt Sturgeon	This won't support `foo = { config,...}: { marker_b = "bar"; }`. Type checking is done before merging, but after resolving `mkIf` (etc) wrappers. Type checking is used to determine which type to use for merging.	20:39:18
h7x4	Aha, that makes sense 👍️	20:41:25
SomeoneSerge (UTC+U[-12,12])	Sounds like `__result` is least wrong?	20:50:51
SomeoneSerge (UTC+U[-12,12])	* Sounds like `__result` is the least wrong?	20:50:55
SomeoneSerge (UTC+U[-12,12])	H'm what if `freeformType`s are different? `attrsOf a` and `attrsOf b`	20:53:42
Matt Sturgeon	I believe the freeform type can be conditional on a marker option being defined without infinite recursion.	20:58:27
Matt Sturgeon	So long as the marker options are explicitly defined, they are resolved before freeform definitions	20:59:14
SomeoneSerge (UTC+U[-12,12])	Not sure I should depend on this detail 😅	20:59:19
Matt Sturgeon	* So long as the marker options are explicitly declared, they are resolved before freeform definitions	20:59:26
Matt Sturgeon	freeformType is itself an option (`config._module.freeformType`), so it's not really an implementation detail	21:00:17

I believe the attrs are merged before being typechecked. I suppose you could try adding a lib.trace inside the typecheck to verify?

20:32:31

SomeoneSerge (UTC+U[-12,12])

trace: { below = "_"; }                                                                                                                                                                                              
trace: { marker_b = "bar"; }                                                                                                                                                                                         
trace: { above = "_"; }                                                                                                                                                                                              
trace: { below = "_"; }                                                                                                                                                                                              
{ foo = { above = "_"; below = "_"; marker_b = "bar"; }; }

For modules:

    { foo = { above = "_"; }; }
    {
      foo.marker_b = "bar";
    }
    { foo = { below = "_"; }; }

20:37:22

SomeoneSerge (UTC+U[-12,12])

*

trace: { below = "_"; }                                                                                                                                                                                              
trace: { marker_b = "bar"; }                                                                                                                                                                                         
trace: { above = "_"; }                                                                                                                                                                                              
trace: { below = "_"; }                                                                                                                                                                                              
{ foo = { above = "_"; below = "_"; marker_b = "bar"; }; }

For modules:

    { foo = { above = "_"; }; }
    {
      foo.marker_b = "bar";
    }
    { foo = { below = "_"; }; }

20:37:32

Matt Sturgeon

This won't support foo = { config,...}: { marker_b = "bar"; }.

Type checking is done before merging, but after resolving mkIf (etc) wrappers.

Type checking is used to determine which type to use for merging.