Reddit reviews Wizard's Bane (Wiz Biz Book 1)

I read a(n American written) novel where a programmer from our world got summoned into another world with magic. He's trash at the highly formalized magic they're used to, but he figures out how to make daemons (that manifest as actual demons) and other magical programs using a hacked together magical programming language.

[edit] Wizard's Bane is the name of the book.

The Apprentice Adept series is close to your description. The SciFi portion is in the far future.

Wizard's Bane also known as Wiz Biz is about a computer programmer whisked away to a fantasy world where he uses his programming skills to write powerful spells based on simple spells. It's a comedic novel.

The Two Year Emperor ($9, but the free version can be found here) also fits. A human is summoned and forced to lead a nation that runs on D&D-ish rules.

Spoiler alert: D&D-ish rulesets are completely, utterly broken when there's no GM to step in.

Oh, and there's Erfworld which also fits if you can stand webcomics - a WH40K(ish) player gets summoned and is forced to act as general for his summoner. This is much closer to "human as familiar", the others in this post are closer to "human summoned by magic is the prophesied hero"

Also the Wizardry series by Rick Cook - a hacker is summoned into a world where magic is deterministic.

Not really litrpg, but i always liked how programming and magic was portrayed in Rick Cook's Wiz Biz series.

https://www.amazon.com/gp/aw/d/B00BER5FS0/ref=dbs_a_w_dp_b00ber5fs0

Basic premise is a computer programmer from our world is summoned to a fantasy world and proceeds to hack and rewrite the rules of magic as if it was a programming language.

Rick Cook's Wizard's Bane series is about a programmer who gets sent to a magic-filled world. And he then proceeds to learn magic, and build his own magic compiler by using ordered simple spells.

Light On Shattered Water is a book about a hiker who gets transported to a world of cat-people in the middle ages. Notable for not being one of those books where "everything magically works out". He doesn't speak the language. He gets treated as non-sentient a lot. Pretty badly brutalized at points too. Eventually starts a semi-industrial-revolution.

I read something in the late 80's that was very similar in concept:

Rick Cook's Wizard's Bane

A computer nerd gets transported to a realm of magic, but learns to write and combine spells like computer code to win the day

Relevant book recommendation: Wizard's Bane and following series, by Rick Cook.
Synopsis: basically like the programmer's physics in Friendship is Optimal, but a little bit more fleshed-out and with some neat ideas. For example, in order to prevent undefined behavior, the magic-programmer builds and formally verifies magical "assembly" instructions, and then builds several no-common-ground compilers and only allows a build to go forward if the compilers produce identical assembly.

Not litRPG but Wizard's Bane by Rick Cook.
"Worth the Candle" has many different magic systems but one involves accessing the world's source code.