Unison of course works this way, as has been mentioned.
I like Deno for similar reason. It's a coarser level of granularity, and not explicitly content-addressed, but you can import specific versions of modules that are ostensibly immutable, and if you want, you could do single-function modules.
I like the idea so much that I'm now kind of put off by any language/runtime that requires users of my app/library to do a separate 'package install' step. Python being the most egregious, but even languages that I am otherwise interested in, like Racket, I avoid because "I want imports to be unambiguous and automatically downloaded."
Having a one-step way to run a program where all dependencies are completely unambiguous might be my #1 requirement for programming languages. I am weird.
One reason not to do things this way is if you want to be able to upgrade some library independently of other components that depend on it, but "that's what dependency injection is for". i.e. have your library take the other library as an argument, with the types/APIs being in a separate one. TypeScript's type system in particular makes this work very easily. I have done this in Deno projects to great effect. From what I've heard from Rich Hickey[1] the pattern should also work well in Clojure
[1] something something union types being superior to what you might call 'sum types'; can't find the link right now. I think this causes some trouble in functional languages where instead of something being A|B it has to be a C, where C = C A | C B. In the former case an A is a valid A|B, but a C A is not an A, so you can't expand the set of values a function takes without breaking the API. Basically what union types require is that every value in the language extends some universal tagged type; if you need to add a tag to your union then it won't work.
I like Deno for similar reason. It's a coarser level of granularity, and not explicitly content-addressed, but you can import specific versions of modules that are ostensibly immutable, and if you want, you could do single-function modules.
I like the idea so much that I'm now kind of put off by any language/runtime that requires users of my app/library to do a separate 'package install' step. Python being the most egregious, but even languages that I am otherwise interested in, like Racket, I avoid because "I want imports to be unambiguous and automatically downloaded."
Having a one-step way to run a program where all dependencies are completely unambiguous might be my #1 requirement for programming languages. I am weird.
One reason not to do things this way is if you want to be able to upgrade some library independently of other components that depend on it, but "that's what dependency injection is for". i.e. have your library take the other library as an argument, with the types/APIs being in a separate one. TypeScript's type system in particular makes this work very easily. I have done this in Deno projects to great effect. From what I've heard from Rich Hickey[1] the pattern should also work well in Clojure
[1] something something union types being superior to what you might call 'sum types'; can't find the link right now. I think this causes some trouble in functional languages where instead of something being A|B it has to be a C, where C = C A | C B. In the former case an A is a valid A|B, but a C A is not an A, so you can't expand the set of values a function takes without breaking the API. Basically what union types require is that every value in the language extends some universal tagged type; if you need to add a tag to your union then it won't work.