k | K Framework Tools | Compiler library
kandi X-RAY | k Summary
kandi X-RAY | k Summary
The K Framework is a tool for designing and modeling programming languages and software/hardware systems. At the core of the K Framework is a programming, modeling, and specification language called K. The K Framework includes tools for compiling K specifications to build interpreters, model checkers, verifiers, associated documentation, and more.
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Top functions reviewed by kandi - BETA
- Unify the given builtin map
- Verify that the given pattern set matches
- Unifies the given builtin list
- Unifies the pattern
- Creates Rewriter
- Convert a module
- Runs a command in the given working directory
- Run the algorithm
- Runs the verification
- Unify the map
- Utility method to compare two sync nodes
- Step 1
- Performs the transformation on the given k item
- Performs an associative match on the subject and pattern
- Starting with the given pattern
- Compute the first set
- Generate kore
- Runs the module
- Initialize the default sort variables
- Determine directory
- Applies any ANY rules to the list
- 1 2 2
- Implementation of kore
- Compiles the template
- Get the scanner
- prove a rule has a boundary
k Key Features
k Examples and Code Snippets
const kNearestNeighbors = (data, labels, point, k = 3) => {
const kNearest = data
.map((el, i) => ({
dist: Math.hypot(...Object.keys(el).map(key => point[key] - el[key])),
label: labels[i]
}))
.sort((a, b) => a.d
def _streaming_sparse_average_precision_at_top_k(labels,
predictions_idx,
weights=None,
metrics_collect
def recall_at_k(labels,
predictions,
k,
class_id=None,
weights=None,
metrics_collections=None,
updates_collections=None,
name=None):
"""
def precision_at_top_k(labels,
predictions_idx,
k=None,
class_id=None,
weights=None,
metrics_collections=None,
u
Community Discussions
Trending Discussions on k
QUESTION
In the current stable Rust, is there a way to write a function equivalent to BTreeMap::pop_last?
The best I could come up with is:
...ANSWER
Answered 2022-Mar-15 at 16:55Is there a way to work around this issue without imposing additional constraints on map key and value types?
It doesn't appear doable in safe Rust, at least not with reasonable algorithmic complexity. (See Aiden4's answer for a solution that does it by re-building the whole map.)
But if you're allowed to use unsafe, and if you're determined enough that you want to delve into it, this code could do it:
QUESTION
A coworker shared this code with me:
...ANSWER
Answered 2022-Jan-09 at 00:42[temp.names]/5 says that a name prefixed by template
must be a template-id, meaning that it must have a template argument list. (Or it can refer to a class/alias template without template argument list, but this is deprecated in the current draft as a result of P1787R6 authored by @DavisHerring.)
There is even an example almost identical to yours under it, identifying your use of template
as ill-formed.
The requirement and example comes from CWG defect report 96, in which the possible ambiguity without the requirement is considered.
Open GCC bug report for this is here. I was not able to find a Clang bug report, but searching for it isn't that easy. Its implementation status page for defect reports however does list the defect report as unimplemented.
QUESTION
I need help to make the snippet below. I need to merge two files and performs computation on matched lines
I have oldFile.txt which contains old data and newFile.txt with an updated sets of data.
I need to to update the oldFile.txt based on the data in the newFile.txt and compute the changes in percentage. Any idea will be very helpful. Thanks in advance
...ANSWER
Answered 2021-Dec-10 at 13:31Here is a sample code to output what you need.
I use the formula below to calculate pct change.
percentage_change = 100*(new-old)/old
If old is 0 it is changed to 1 to avoid division by zero error.
QUESTION
I'm looking for a way to have all keys / values pair of a nested object.
(For the autocomplete of MongoDB dot notation key / value type)
...ANSWER
Answered 2021-Dec-02 at 09:30In order to achieve this goal we need to create permutation of all allowed paths. For example:
QUESTION
I am trying to implement a reasonably fast version of Floyd-Warshall algorithm in Rust. This algorithm finds a shortest paths between all vertices in a directed weighted graph.
The main part of the algorithm could be written like this:
...ANSWER
Answered 2021-Nov-21 at 19:55At first blush, one would hope this would be enough:
QUESTION
I am trying to find a more efficient solution to a combinatorics problem than the solution I have already found.
Suppose I have a set of N objects (indexed 0..N-1) and wish to consider each subset of size K (0<=K<=N). There are S=C(N,K) (i.e., "N choose K") such subsets. I wish to map (or "encode") each such subset to a unique integer in the range 0..S-1.
Using N=7 (i.e., indexes are 0..6) and K=4 (S=35) as an example, the following mapping is the goal:
0 1 2 3 --> 0
0 1 2 4 --> 1
...
2 4 5 6 --> 33
3 4 5 6 --> 34
N and K were chosen small for the purposes of illustration. However, in my actual application, C(N,K) is far too large to obtain these mappings from a lookup table. They must be computed on-the-fly.
In the code that follows, combinations_table
is a pre-computed two-dimensional array for fast lookup of C(N,K) values.
All code given is compliant with the C++14 standard.
If the objects in a subset are ordered by increasing order of their indexes, the following code will compute that subset's encoding:
...ANSWER
Answered 2021-Oct-21 at 02:18Take a look at the recursive formula for combinations:
Suppose you have a combination space C(n,k)
. You can divide that space into two subspaces:
C(n-1,k-1)
all combinations, where the first element of the original set (of lengthn
) is presentC(n-1, k)
where first element is not preset
If you have an index X that corresponds to a combination from C(n,k)
, you can identify whether the first element of your original set belongs to the subset (which corresponds to X
), if you check whether X
belongs to either subspace:
X < C(n-1, k-1)
: belongsX >= C(n-1, k-1)
: doesn't belong
Then you can recursively apply the same approach for C(n-1, ...)
and so on, until you've found the answer for all n
elements of the original set.
Python code to illustrate this approach:
QUESTION
In short:
I have implemented a simple (multi-key) hash table with buckets (containing several elements) that exactly fit a cacheline. Inserting into a cacheline bucket is very simple, and the critical part of the main loop.
I have implemented three versions that produce the same outcome and should behave the same.
The mystery
However, I'm seeing wild performance differences by a surprisingly large factor 3, despite all versions having the exact same cacheline access pattern and resulting in identical hash table data.
The best implementation insert_ok
suffers around a factor 3 slow down compared to insert_bad
& insert_alt
on my CPU (i7-7700HQ).
One variant insert_bad is a simple modification of insert_ok
that adds an extra unnecessary linear search within the cacheline to find the position to write to (which it already knows) and does not suffer this x3 slow down.
The exact same executable shows insert_ok
a factor 1.6 faster compared to insert_bad
& insert_alt
on other CPUs (AMD 5950X (Zen 3), Intel i7-11800H (Tiger Lake)).
ANSWER
Answered 2021-Oct-25 at 22:53The TLDR is that loads which miss all levels of the TLB (and so require a page walk) and which are separated by address unknown stores can't execute in parallel, i.e., the loads are serialized and the memory level parallelism (MLP) factor is capped at 1. Effectively, the stores fence the loads, much as lfence
would.
The slow version of your insert function results in this scenario, while the other two don't (the store address is known). For large region sizes the memory access pattern dominates, and the performance is almost directly related to the MLP: the fast versions can overlap load misses and get an MLP of about 3, resulting in a 3x speedup (and the narrower reproduction case we discuss below can show more than a 10x difference on Skylake).
The underlying reason seems to be that the Skylake processor tries to maintain page-table coherence, which is not required by the specification but can work around bugs in software.
The DetailsFor those who are interested, we'll dig into the details of what's going on.
I could reproduce the problem immediately on my Skylake i7-6700HQ machine, and by stripping out extraneous parts we can reduce the original hash insert benchmark to this simple loop, which exhibits the same issue:
QUESTION
Say we have this
...ANSWER
Answered 2021-Oct-22 at 18:20a, b = (c, d)
unpacks the tuple from left to right and assigns a = c
and b = d
in that order.
x.items()
iterates over key-value pairs in x
. E.g. doing list(x.items())
will give [('a', 1), ('b', 2)]
for a, b in x.items()
assigns the key to a
, and the value to b
for each key-value pair in x
.
for k, y[k] in x.items()
assigns the key to k
, and the value to y[k]
for each key-value pair in x
.
You can use k
in y[k]
because k
has already been assigned since unpacking happens left-right
You don't need to do anything in the loop because whatever you needed is done already.
Because the loop already assigned every value in x
to y[k]
, y
is now a shallow copy of x
.
As the tweet you reference says, this is indeed a "terse, unintuitive, and confusing" way to do x.copy()
QUESTION
In order to improve the performance of writing data into std::string
, C++23 specially introduced resize_and_overwrite()
for std::string
. In [string.capacity], the standard describes it as follows:
...
ANSWER
Answered 2021-Oct-18 at 16:38op
is only called once before it is destroyed, so calling it as an rvalue permits any &&
overload on it to reuse any resources it might hold.
The callable object is morally an xvalue - it is "expiring" because it is destroyed immediately after the call. If you specifically designed your callable to only support calling as lvalues, then the library is happy to oblige by preventing this from working.
QUESTION
I was checking the code of the toolz library's groupby
function in Python and I found this:
ANSWER
Answered 2021-Sep-22 at 13:05This is a somewhat confusing trick to save a small amount of time:
We are creating a defaultdict
with a factory function that returns a bound append
method of a new list instance with [].append
. Then we can just do d[key(item)](item)
instead of d[key(item)].append(item)
like we would have if we create a defaultdict
that contains lists. If we don't lookup append
everytime, we gain a small amount of time.
But now the dict
contains bound methods instead of the lists, so we have to get the original list instance back via __self__
.
__self__
is an attribute described for instance methods that returns the original instance. You can verify that with this for example:
Community Discussions, Code Snippets contain sources that include Stack Exchange Network
Vulnerabilities
No vulnerabilities reported
Install k
Java Development Kit (required JDK11 or higher). To make sure that everything works you should be able to call java -version and javac -version from a terminal. Maven usually requires setting an environment variable JAVA_HOME pointing to the installation directory of the JDK (not to be mistaken with JRE). You can test if it works by calling mvn -version in a terminal. This will provide the information about the JDK Maven is using, in case it is the wrong one. To install, go to https://docs.haskellstack.org/en/stable/README/ and follow the instructions. You may need to do stack upgrade to ensure the latest version of Haskell Stack.
Java Development Kit (required JDK11 or higher) Linux: Download from package manager (e.g. sudo apt-get install openjdk-11-jdk). macOS/brew: Download from package manager (e.g. brew install java). To make sure that everything works you should be able to call java -version and javac -version from a terminal.
LLVM macOS/brew: Since LLVM is distributed as a keg-only package, we must explicitly make it available for command line usage. See the results of the brew info llvm command for more information on how to do this.
Flex / Bison macOS/brew: The versions of these packages supplied by the OS are too old, and are not compatible with the K build. You must ensure that the Homebrew-installed versions are first on your PATH when building K (i.e. which flex is not /usr/bin/flex).
Apache Maven Linux: Download from package manager (e.g. sudo apt-get install maven). macOS/brew: Download it from a package manager or from http://maven.apache.org/download.cgi and follow the instructions on the webpage. Maven usually requires setting an environment variable JAVA_HOME pointing to the installation directory of the JDK (not to be mistaken with JRE). You can test if it works by calling mvn -version in a terminal. This will provide the information about the JDK Maven is using, in case it is the wrong one.
Haskell Stack To install, go to https://docs.haskellstack.org/en/stable/README/ and follow the instructions. You may need to do stack upgrade to ensure the latest version of Haskell Stack.
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