Internal Categories as Change Structures

Existentials and custom change types

Fitch-style modal logic & the indiscrete modality & modal subtyping

Boomfun: lists/monoids & multisets/c.monoids

self-maintainable functions & linearity?

transducers as derivatives

DBSP: Automatic Incremental View Maintenance for Rich Query Languages https://arxiv.org/pdf/2203.16684.pdf

reverse mode incrementalization

lenses?
matthijs vakar & tom smeding: linearity & reverse mode linear things can be evaluated in reverse they generalize reverse mode to type-with-monoid? "reverse AD at higher types": https://arxiv.org/abs/2007.05283 or "dual-numbers reverse ad, efficiently"?

switch to applicative syntax (not monadic) for relational algebra

can this make compiling to efficient joins easier?

What else would I like to do?

voice control intersect PL/tooling design?
PL intersect DB/query languages, incrementalization https://riffle.systems/essays/prelude/
how do you turn a language design into a library design?