matryoshka | Generalized recursion schemes and traversals for Scala

by precog Scala Version: Current License: Apache-2.0

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kandi X-RAY | matryoshka Summary

matryoshka is a Scala library. matryoshka has no bugs, it has no vulnerabilities, it has a Permissive License and it has medium support. You can download it from GitHub.

This library is predicated on the idea of rewriting your recursive data structures, replacing the recursive type reference with a fresh type parameter. could be rewritten as. This abstract class generally allows a Traverse instance (or at least a Functor instance). Then you use one of the fixed point type constructors below to regain your recursive type. You may also want instances for Delay[Equal, ?], Delay[Order, ?], and Delay[Show, ?] (which are very similar to their non-Delay equivalents) to get instances for fixed points of your functor.

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Support

matryoshka has a medium active ecosystem.

It has 773 star(s) with 93 fork(s). There are 56 watchers for this library.

It had no major release in the last 6 months.

There are 14 open issues and 9 have been closed. On average issues are closed in 165 days. There are 5 open pull requests and 0 closed requests.

It has a neutral sentiment in the developer community.

The latest version of matryoshka is current.

Quality

matryoshka has 0 bugs and 0 code smells.

Security

matryoshka has no vulnerabilities reported, and its dependent libraries have no vulnerabilities reported.

matryoshka code analysis shows 0 unresolved vulnerabilities.

There are 0 security hotspots that need review.

License

matryoshka is licensed under the Apache-2.0 License. This license is Permissive.

Permissive licenses have the least restrictions, and you can use them in most projects.

Reuse

matryoshka releases are not available. You will need to build from source code and install.

Installation instructions are not available. Examples and code snippets are available.

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Community Discussions

Trending Discussions on matryoshka

Having problem with array of struct solving a problem in C

How to model/formalize the change of the variable (change of world) in Isabelle/HOL?

QUESTION

Having problem with array of struct solving a problem in C

Asked 2021-May-09 at 07:15

I'm trying to figure out how to solve this problem:

We have n ≥ 1 parallelepiped-shaped boxes, labeled as 0, 1,… n - 1; box i has width x [i], height y [i] and depth z [i] (strictly positive real values).
We want to insert as many boxes one inside the other, similar to a "matryoshka": box i can be contained in box j if the dimensions of box i are strictly smaller than the corresponding ones of box j, that is, if x [i] Implement an efficient algorithm to determine the maximum number of boxes that can be inserted into each other respecting the previous constraints. The boxes cannot be rotated. The program accepts a single parameter on the command line that represents the name of the input file, the content of which has the following structure:
n
x [0] y [0] z [0]
...
x [n-1] y [n-1] z [n-1]
The output must list the boxes that are part of the optimal solution, one box per line, starting with the outermost one; for each of them the dimensions must be reported (as per input file).

...

ANSWER

Answered 2021-May-08 at 09:34

You can solve the problem by topological sorting the boxes according to "contains" relation and use dynamic programming to track how long chain of boxes can be put into previous boxes. Start from the boxes that contains no other boxes. When you add a new box just iterate over boxes that fit to the given to find the one with the longest chain that fits to the current box.

Finally, reconstruct the chain starting from the box with the largest score. Complexity is O(N^2). Here's the code:

Source https://stackoverflow.com/questions/67437278

QUESTION

How to model/formalize the change of the variable (change of world) in Isabelle/HOL?

Asked 2020-Jul-03 at 08:18

I am trying to formalize business rules in Isabelle/HOL, but business rules involve the change of the values of some variables, like if x=5 => x=6. => is not the usual implication there, because x is 5 in one world (interpretation, semantic domain) and after the execution of the rule the x is 6 and it is already a different world (different interpretation, assignment function, semantic domain). So - technically is x=5 => x=6 is not the formula in First Order Logic and it is not also the formula of Higher Order Logic of Isabelle/HOL. More possible is that it is the formula in dynamic/action logic [rule1](x=5)=(x=6) (that defines that upon application of rule1 to the formula in some world yields to the truthful formula in some other world (dynamic/action logic is essentially a kind of modal logic and Kripke/possible world semantics can be applied here).

Now, back to Isabelle/HOL or Coq: FOL/HOL theory is set of formulas in all the worlds or in one particular world. If we stay at FOL/HOL then there is no change of the world, no change of the values of the variables. We should go to the modal logics if we would like to model, reasong about such changes. But can it be done in HOL? This change of world?

http://matryoshka.gforge.inria.fr/pubs/fernandez_burgos_bsc_thesis.pdf is good work about formalization of sorting algorithms in Isabelle/HOL, functional programming is used there and there is no need of variables and hence - no this change among worlds. But if we try to model Reinforcement Learning, Markov processes, impertative/object oriented programming, business rules in Isabelle/HOL, then we should express this change. How to do that?

How to express business rule if x=5 => x=6 in Isabelle/HOL?

The same approach can be used in Coq, that is why answers from the Coq community are welcome as well.

...

ANSWER

Answered 2020-Jul-03 at 06:56

The most common solution is using a predicate of type world => world => bool representing transitions between worlds or states (for Markov processes) or memory (for program verification). It represents a transition from one place to another.

Such a predicate can typically be defined as an inductive predicate to represent non-determinism.

If you are specifically interested in logic:

For Isabelle, you could have a look at how it is done in the formalisation of dynamic logic and of modal logic in the AFP (https://www.isa-afp.org/topics.html -- search for Modal logic: on that page).
For Coq, I have found this approach, which follows the same pattern, but there many other formalisations.

Source https://stackoverflow.com/questions/62709073

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