Why doesn't Scheme support first class environments?

I've been reading through SICP (Structure and Interpration of Computer Programs) and was really excited to discover this wonderful special form: "make-environment", which they demonstrate to use...

Reason for ~100x slowdown with heap memory functions using HEAP_NO_SERIALIZE on Windows Vista and Windows 7

I'm trying to tracedown a huge slowdown in the heap memory functions in Windows Vista and Windows 7 (I didn't test on any server editions). It doesn't happen on Windows XP at all, only on...

Reference — What does this symbol mean in PHP?

What is this? This is a collection of questions that come up every now and then about syntax in PHP. This is also a Community Wiki, so everyone is invited to participate in maintaining this...

Custom callbacks in VBA

Note the tag: VBA, not VB6, not VB.NET. This is specific to VBA in MS Access. I've built a collection of methods in an module I call "Enumerable". It does a lot of things reminiscent of the...

C++ Class wrapper around fundamental types

Many libraries I have seen/used have typedefs to provide portable, fixed size variables, eg int8, uint8, int16, uint16, etc which will be the correct size regardless of platform (and c++11 does it...

Calling a lambda function in GDB

//gdb-call-lambda.cpp #include <iostream> void do_something(void) { ...

Bash double bracket regex comparison using negative lookahead error return 2

On Bash 4.1 machine, I'm trying to use "double bracket" [[ expression ]] to do REGEX comparison using "NEGATIVE LOOKAHEAD". I did "set +H" to disable BASH variable'!' expansion to command history...

Combined Comparison / "Spaceship" Operator (<=>) in Javascript?

Ruby has something called a Combined Comparison or "Spaceship" Operator, it looks like this: <=> It does the following: a <=> b := if a < b then return -1 if a = b then return 0 if a...

Why is `"literal"` encouraged to decay to `const char*` in C++ argument type match?

I'm playing around with overloading operators in c++14, and I tried to match two types of arguments: any-old-const-char*, and a-string-literal. That is, I'm trying to see if I can discriminate...

How to effectively handle errors in Teamcenter ITK C++ code

How do I effectively handle errors thrown by ITK calls in Teamcenter server customization code? In the C ITK APIs, a function typically returns an integer value to denote success/failure. Zero...

Pass a list of strings as parameter of a dependant task in Airflow

I am trying to pass a list of strings from one task to another one via XCom but I do not seem to manage to get the pushed list interpreted back as a list. For example, when I do this in some...

Provide default arguments for subscript operator and function call operator

In the following code, I have provided default arguments for array subscript operator. struct st { int operator[](int x = 0) { // code here } }; But, compiler generated an...

C++17 constexpr string parsing

Sorry that this will be a long post, but I feel like you need all of the code to see what's going on. So, I have been experimenting with an idea for compile time string to data structure parser....

Airflow Python Operator with a. return type

I have a python operator in my DAG. The python callable function is returning a bool value. But, when I run the DAG, I get the below error. TypeError: 'bool' object is not callable I modified...

How to model if-expressions with actor systems?

I'm trying to emulate a simple functional language using an actor based execution model where issues arose modelling if-expression. Actor systems nowadays are used basically for speeding up all...

JS: Object.defineProperty() and Proxy

What's the difference between Object.defineProperty() and Proxy? On my view they do really the same in essence being useful only for implementation of reactivity, validation and defaults. So it...

Unable to install ref-struct module on nodejs 12.14.0

i am trying to install ref-struct module using following command : npm install ref-struct Environment specification : nodejs : 12.14.0 npm : 6.13.4 Error i am getting error : [![enter image...

Remove undefined from type

I use typeof to infer the return type of a function, but since I cannot call the actual function I use a trick using the ternary operator to infer the type, however this leaves me with a union...

npm install issues TypeError: Cannot read property 'match' of undefined

I'm having massive issues installing the packages via npm. I'm getting nothing but this log as an output and have no idea where or how to fix this issue. 0 info it worked if it ends with ok 1...

Invoking "make -j4 -l4" failed

I am trying to install the ego-planner package. When I run catkin_make, I get an error. I am running ROS Melodic on Ubuntu 18.04. How do I fix this? This is the output I get (I have included most...

Why operator inside parenthesis changes `this` in function call

Talk is cheap; show me the code. // equals to this.test = "inside window" var test = "inside window"; function f () { console.log(this.test) }; var obj = { test: "inside object", fn:...

How "vars" in Jenkins Shared Libraries work?

I'm experiencing some behaviors in Jenkins Shared Libraries, and it'll be great if someone can explain this to me: First issue Let's say i have a file in the vars directory: //...

Why is std::codecvt only used by file I/O streams?

I've been implementing a codecvt for handling indentiation of output streams. It can be used like this and works fine: std::cout << indenter::push << "im indentet" << indenter::pop << "\n im...

Understanding error when using partial function application or curry in conjunction with overload and std::visit

tl;dr I'd like to understand what's wrong with the first code below, i.e. what the error is telling me. MRE I've been able to shorten the example to the following, which generates the same error...

EasyAdmin 3: how to retrieve edit form values

I am using EasyAdmin 3 and I am trying to create a validation system where: ROLE_EDITOR can edit an Entity (e.g. Operateur) via EasyAdmin (OperateurCrudCrontroller) and the edited data of this...

How to invoke a cloud function from google cloud composer?

For a requirement I want to call/invoke a cloud function from inside a cloud composer pipeline but I cant find much info on it, I tried using SimpleHTTP airflow operator but I get this...

Deploy CloudFunctions in VPC SC with cloud build

On GCP project, protected using VPC Service Control,I tried to deploy cloud functions with Cloud Build, but got error when deploy with gcloud command. Procedure 1 add cloudbuild service account in...

How to implement Go's defer() in C so that it allows declaring vars?

In this Modern C video there's a trick that allows to postpone execution of a code until the block/scope exits. It's used as follows: int main() { int foo=0, bar; const char *etc = "Some...

Does the Hack-style pipe operator |> take precedence over grouping operator ( ) in order of operations in JavaScript?

Does the Hack-style pipe operator |> take precedence over grouping operator ( ) in order of operations in JavaScript? I'm investigating tc39/proposal-pipeline-operator - for JavaScript Pipe...

What is context variable in Airflow operators

I'm trying to understand what is this variable called context in Airflow operators. as example: def execute(self, **context**). Where it comes from? where can I set it? when and how can I use it...