Fructose – LLM calls as strongly typed functions
Hi HN! Erik here from Banana (formerly the serverless GPU platform), excited to show you what we’ve been working on next: Fructose Fructose is a python package to call LLMs as strongly typed functions. It uses function type signatures to guide the generation and guarantee a correctly typed output, in whatever basic/complex python datatype requested. By guaranteeing output structure, we believe this will enable more complex applications to be built, interweaving code with LLMs with code. For now, we’ve shipped Fructose as a client-only library simply calling gpt-4 (by default) with json…
In plain words
Fructose is a Python package that enables developers to call large language models as strongly typed functions. It uses function type signatures to guarantee that LLM outputs match requested data structures, whether simple or complex Python types. Currently working with GPT-4 via JSON mode, Fructose aims to make it easier to build complex applications that integrate LLM calls seamlessly with traditional code logic.
written from the facts on this page · September 2026
From the sources
In the maker’s words, at launch
Hi HN! Erik here from Banana (formerly the serverless GPU platform), excited to show you what we’ve been working on next: Fructose Fructose is a python package to call LLMs as strongly typed functions. It uses function type signatures to guide the generation and guarantee a correctly typed output, in whatever basic/complex python datatype requested. By guaranteeing output structure, we believe this will enable more complex applications to be built, interweaving code with LLMs with code. For now, we’ve shipped Fructose as a client-only library simply calling gpt-4 (by default) with json mode, pretty simple and not unlike other packages such as marvin and instructor, but we’re also working on our own lightweight formatting model that we’ll host and/or distribute to the client, to help reduce token burn and increase accuracy. We figure, no time like the present to show y’all what we’re working on! Questions, compliments, and roasts welcomed.
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