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- Hacker News
- I'm a retard so I'm gonna call it Half Life.by opengrass
- how do i search for a character i can't even type?
are people in this field just able to jump into Greek mode?
by wigster - I am curious why develop a new language instead of building a library for an existing language. What are the benefits as I didn't see this in the paper? Can it interact with other languages?by ktallett
- The first sentence of the abstract gives a motivation: "λλ uses a linear type system to encode the physical constraints of optics, rejecting unrealizable programs at compile time."
The fact that it its own language does not preclude using it within the context of a different language. You can embed a domain specific language into a general purpose one.
by black_knight - I understood this language like being something similar to assembly.
Many compiled languages can compile down to assembly and which can be used to debug/optimize/understand the compilation process.
Assembly is so close to the underlying hardware that it's not very practical for us humans to write software with it.
> Can it interact with other languages?
I'd say this is probably similar to the story with assembly. Assembly cannot interop with C. But C can be compiled down to assembly (not sure that counts as "interact" to you).
by flossly - The second λ is subscripted. As footnote 1 in the paper says:
> Pronounced “lambda lambda”. One λ refers to the λ-calculus and the other refers to an optical wavelength.
by tromp - lambdi!by esseph
- Ah, the bi-lams.by noworld
- Or, in French, Lambdeux.by sunrunner
- Full syntax of λλ (from the paper):
e ::= v | x | input(p) | let x = e1 in e2 | (e1, e2) | unpack e1 as (x1, x2) in e2 | phase(θ, e) | split(r, e) | unitary(U, (e1, e2)) | output(p) <- e1; e2 v ::= r ↓ ℝ | p ↓ Port | U ↓ Unitary | () τ ::= ℝ | Port | Opt | Unitary | Unit |(τ1 * τ2)by deepsun - So simplified, a bit like System F.by pjmlp
- Note that this is not an extension of the pure λ-calculus.
Abstraction (λx.e) and application (f a) are missing, although the let construct "let x = e1 in e2" is equivalent to their combination ((λx.e2) e1).
The paper has few details on the higher-level specification language in which users specify desired behaviour:
> Specification Language. Specifications are written as relations between input and output ports, expressed using linear expressions. On their own, specifications are not λ _λ programs. It is the job of the synthesizer to find λ _λ programs that realize a given specification. For example, a simple switching behavior can be specified as output[i] = input[j], while a 2x2 AllReduce operation can be written as output[1] = (input[1] + input[2])/sqrt(2) and output[2]= (input[1] - input[2])/sqrt(2).
by tromp