den.lib (deprecated)

`den.lib.parametric`

Historically wrapped an aspect to filter includes by argument compatibility. The fx pipeline now resolves parametric dispatch directly, so parametric and parametric.atLeast / parametric.exactly are identity passthroughs that emit a deprecation warning. Each call logs den.lib.parametric: … is deprecated.

# Deprecated — pass the plain attrset directly instead.
den.lib.parametric { nixos.x = 1; includes = [ ... ]; }

`den.lib.parametric.atLeast`

Identity passthrough (warns). Previously: match when all required params are present.

`den.lib.parametric.exactly`

Identity passthrough (warns). Previously: match only when required params exactly equal provided params.

den.lib.parametric.exactly { includes = [ ({ host }: ...) ]; }

`den.lib.parametric.fixedTo`

Pins context values for the aspect via scope handlers (constantHandler), so the aspect resolves as if those values were in scope. Returns a parametric wrapper and warns. Variants .exactly, .atLeast, and .upTo behave the same.

den.lib.parametric.fixedTo { host = myHost; } someAspect

`den.lib.parametric.expands`

Merges additional attributes into the aspect’s scope handlers before dispatch. Returns a parametric wrapper and warns.

den.lib.parametric.expands { extra = true; } someAspect

`den.lib.canTake`

Function argument introspection. A pure predicate (it does not warn), still used internally by the type system; prefer plain parametric functions in new code.

`den.lib.canTake params fn`

Returns true if fn’s required arguments are satisfied by params (atLeast).

`den.lib.canTake.atLeast params fn`

Same as canTake.

`den.lib.canTake.exactly params fn`

Returns true only if fn’s required arguments exactly match params.

`den.lib.canTake.upTo params fn`

Returns true if fn is satisfied by params and at least one of params overlaps fn’s arguments.

`den.lib.take`

Context-level guards. Under handler-based resolution the pipeline resolves function arguments automatically, so most of these now warn.

`den.lib.take.exactly fn`

Returns a parametric wrapper that calls fn only when the resolved context matches fn’s declared arguments exactly (no extra context keys). Warns.

`den.lib.take.atLeast fn`

Identity passthrough (warns). The pipeline’s deferral already provides atLeast semantics.

`den.lib.take.upTo fn`

Identity passthrough (warns).

`den.lib.take.unused`

_unused: used: used — ignores the first argument, returns the second. A plain helper (does not warn).

Context shortcuts

Wrap an aspect so it requires a specific set of context keys. Each returns a parametric wrapper and warns. They are now thin aliases for a plain function with the same keys — i.e. den.lib.perHost f behaves as ({ host, ... }: f { … }): the arg binds once at the emitting scope if in-ctx, fans out class-locally over that scope’s descendants otherwise, and is inert if misplaced. Prefer the plain function form, e.g. ({ host, user, ... }: { ... }).

`den.lib.perHost aspect`

Wrap aspect to require { host }.

`den.lib.perUser aspect`

Wrap aspect to require { host, user }.

`den.lib.perHome aspect`

Wrap aspect to require { home }.

`den.lib.resolveStage`

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