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This is just wrong, you're being too didactic. Idris specifically lets you implement nontotal functions in the same way that Rust lets you write memory-unsafe c

This is just wrong, you're being too didactic. Idris specifically lets you implement nontotal functions in the same way that Rust lets you write memory-unsafe code. The idea is you isolate it to the part of the program with effects (including the main loop), which the compiler can't verify anyway, and leave the total formally verified stuff to the business logic. Anything that's marked as total is proven safe, so you only need to worry about a few ugly bits; just like unsafe Rust. Idris absolutely is a general-purpose functional language in the ML family. It is Haskell, but boosted with dependent types.

andai 6mo ago
Random passerby chiming in: so this means you can write "regular" software with this stuff? While reading TFA I thought the theorem stuff deserved its own category, but I guess it's a specialization within an ur-family (several), rather than its own family? It definitely sounds like it deserves its own category of programming language, though. The same way Lojban has ancestry in many natural languages but is very much doing its own thing.
- nextaccountic 6mo ago
  Yes Idris was meant to write regular code. F* is also meant to write regular code But I think that the theorem prover that excels most at regular code is actually Lean. The reason I think that is because Lean has a growing community, or at least is growing much faster than other similar languages, and for regular code you really need a healthy ecosystem of libraries and stuff. Anyway here an article about Lean as a general purpose language https://kirancodes.me/posts/log-ocaml-to-lean.html https://kirancodes.me/posts/log-ocaml-to-lean.html
  - Hendrikto 6mo ago
    > if you're a developer who wants to exploit the multiplicative factor of a truly flexible and extensible programming language with state of the art features from the cutting-edge of PL research, then maybe give Lean a whirl! Does not sound that appealing to me. Sounds like little consistency and having to learn a new language for every project.
nextaccountic 6mo ago
I mentioned this later > You can separate terms that can be used in proofs (those must be total) from terms that can only be used in computations (those can be Turing complete), like in Lean What I meant is that the part of Idris that lets people prove theorems is the non-total part But, I think you are right. Haskell could go there by adding a keyword to mark total functions, rather than marking nontotal functions like Idris does. It's otherwise very similar languages
- pyrale 6mo ago
  Haskell has liquid haskell to do that.

andai 6mo ago

Random passerby chiming in: so this means you can write "regular" software with this stuff? While reading TFA I thought the theorem stuff deserved its own category, but I guess it's a specialization within an ur-family (several), rather than its own family? It definitely sounds like it deserves its own category of programming language, though. The same way Lojban has ancestry in many natural languages but is very much doing its own thing.

nextaccountic 6mo ago
Yes Idris was meant to write regular code. F* is also meant to write regular code But I think that the theorem prover that excels most at regular code is actually Lean. The reason I think that is because Lean has a growing community, or at least is growing much faster than other similar languages, and for regular code you really need a healthy ecosystem of libraries and stuff. Anyway here an article about Lean as a general purpose language https://kirancodes.me/posts/log-ocaml-to-lean.html https://kirancodes.me/posts/log-ocaml-to-lean.html
- Hendrikto 6mo ago
  > if you're a developer who wants to exploit the multiplicative factor of a truly flexible and extensible programming language with state of the art features from the cutting-edge of PL research, then maybe give Lean a whirl! Does not sound that appealing to me. Sounds like little consistency and having to learn a new language for every project.

nextaccountic 6mo ago

I mentioned this later > You can separate terms that can be used in proofs (those must be total) from terms that can only be used in computations (those can be Turing complete), like in Lean What I meant is that the part of Idris that lets people prove theorems is the non-total part But, I think you are right. Haskell could go there by adding a keyword to mark total functions, rather than marking nontotal functions like Idris does. It's otherwise very similar languages

pyrale 6mo ago
Haskell has liquid haskell to do that.