[fouric]

For Common Lispers such as myself, who are vaguely aware of developments in the Scheme space: the most important difference between CRUNCH and Chicken appears to be that, while both compile down to C/object code, CRUNCH is additionally targeting a statically-typed subset of Scheme.

Opinion: this is great. The aversion of Lispers to static types is historical rather than intrinsic and reflects the relative difference in expressiveness between program semantics and type semantics (and runtime vs tooling) for much of computing. Now that types and tools are advancing, static Lisps are feasible, and I love that.

[dokyun]

I don't believe it's not intrinsic. A lot of the reason why Lispers may be averse to static types is because of the perceived inflexibility it can induce into the system. Lisp programmers don't want to be told what to do, especially by the compiler. Some CLs like SBCL have allowed some form of inference through the standard type declarations in the language. This leads me to believe that the 'right thing' in the case of Lisp is a combination of dynamicity and some stronger typing features that can be applied during the optimization stage. The dynamic nature and ease of use of Lisp relative to its performance is one of its greatest assets: it would be nearsighted to try and sacrifice that--a good Lisp programmer can optimize the important parts of his programs such that they're comparable to or even outperform their equivalents in other more ``high-performance'' languages. With that being said, these developments might bring us closer to a ``sufficiently smart compiler'' that could make that latter stage mostly unnecessary.

[fouric]

> A lot of the reason why Lispers may be averse to static types is because of the perceived inflexibility it can induce into the system.

This perceived inflexibility is what my comment was getting at - that for primitive type systems available back in the 80's, yes, the types significantly constrained the programs you could write. With today's type systems, however, you have far more flexibility, especially those with "Any" types that allow you to "punch a hole in the type system", so to speak.

When I tried typed Python a few years ago, I found out that, to my surprise, 99% of the code that I naturally wrote could have static types attached (or inferred) without modification because of the flexibility of Python's type system.

I also learned that types are a property of programs, more than just languages. If a program is ill-typed, then having a dynamically-typed language will not save you - it will just crash at runtime. Static types are limiting when either (1) they prevent you from writing/expressing well-typed programs because of the inexpressiveness of the type system or (2) it's burdensome to actually express the type to the compiler.

Modern languages and tools present massive advances in both of those areas. Type systems are massively more expressive, so the "false negative" area of valid programs that can't be expressed is much, much smaller. And, with type inference and more expressive types, not only do you sometimes not have to express the type in your source code at all (when it's inferred), but when you do, it's often easier.

The "Any" type is really what steals the show. I don't think that there's a lot of value in a fully statically-typed Lisp where you can't have dynamic values at all - but I think there's a lot of value in a Lisp with a Python-like type system where you start out static and can use "unknown", "any", and "object" to selectively add dynamic types when needed.

Because, being a Lisper, you probably think like me, I'll give you the idea that really convinced me that types are positive value (as opposed to "only" being small negative value): they enable you to build large, complex, and alive systems.

Types are a force-multiplier for our limited human brains. With types, you can more easily build large systems, you can more easily refactor, you can start with a live REPL and more easily transition your code into source on disk. Types help you design and build things - which is why we use Lisps, after all!

[nathan_compton]

I don't think it makes sense to conflate Lispers to Schemers. I've programmed in both languages but have a stronger affinity for Scheme partially because semantically it is less flexible and more "staticy" than Lisp. Philosophically, the languages tend to attract different personalities (to the extent that the highly fragmentary Scheme world can be characterized).

[kazinator]

I want static types in a higher level assembly language for systems programming. That's because I want to work with machine-level representations, in which there are no spare bits for indicating type at run-time (moreover, using such a language, we can design a type system with such bits, in any way we please).

I don't want static types in a high level language.

It's just counterproductive.

We only have to look at numbers to feel how it sucks. If we divide two integers in Common Lisp, if the division is exact, the object that comes out is an integer. Otherwise we get a ratio object. Or if we take a square root of a real, we get a complex number if the input is negative, otherwise real.

This cannot be modeled effectively in a static system. You can use a sum type, but that's just a greenspunned ad hoc dynamic type.

[diggan]

> Now that types and tools are advancing, static Lisps are feasible, and I love that.

Haven't that been feasible for a pretty long time already? Judging by how well-received (or not) they've been, it seems there isn't much demand for it. Things like clojure.spec and alike (compile-time + run-time typing) seems much more popular, but isn't static.

[nesarkvechnep]

There isn’t much demand for Lisps in general.

[jnxx]

What are the main differences between OcamML and a statically typed Lisp?

[packetlost]

Type inference is probably the biggest thing. You would need explicit "phases" to expand macros, disallow macro expansion at runtime, and implement bi-directional type inference HM-style to get even close to what OCaml has.

To be honest, I'd kill for a Lisp that had the same type system as OCaml, but I suspect the closes we'll get is basically Rust (whose macro system is quite good).

[wbl]

The module and functor system. Also macros are much more a Lisp family thing.