Java Kotlin

How to ignore generated Kotlin files in Jacoco?

I am using build.gradle.kts Jacoco: id(“org.barfuin.gradle.jacocolog”) version “3.1.0” Optics from Arrow library Arrow library generates __OpticsKt files that don’t have coverage in Jacoco. How to ignore them in the build.gradle.kts? Answer You need to add tasks.jacocoTestReport { block: How does it work? It seems like Jacoco uses .class files to generate coverage. Check in your […]

javascript typescript

How to achieve validatedNel with fp-ts

fp-ts is a great library, but it can be confusing some times. The last problem that I had was that I didn’t know how to implement validatedNel. Some methods have been deprecated, and the issue answers also didn’t help. ValidatedNel validatedNel is used to validate multiple problems and then merge them together into a single […]


Lazy/conditional logging in JavaScript

I had some trace logs that I only wanted to enable conditionally, eg only when the logging level was set to TRACE. I couldn’t find a node.js library that enables this kind of logging. For each of them, the logger always evaluated the string input. The longRunningTask was always ran, even if trace logging was […]


How to scroll to line with codemirror-react

This is for “@uiw/react-codemirror”: “^4.20.2” capture the ref to the codemirror objects 2. on each new ref callback, call the dispatch with the new selection and scrollIntoView note: I used MUI accordion, and for that the useRef didn’t seem to update when I collapsed and expanded the Accordion. Therefore I needed to update the object […]

Smart Contract Audits Solidity

how to find critical bugs in code4rena contests

I have recently tried my luck with code4rena, where you can earn extra income by finding bugs in Solidity contracts. At first I didn’t find any bugs, only low priority QA issues. However, after a few audits I have improved my process and submitted some critical issues. My process Read the contest details Understand the […]


What is a Knowledge Token?

Knowledge Token is an NFT project that allows content writers to create tokens that readers mint in order to see secret content. Knowledge Tokens are NFT-s stored on the Polygon blockchain. Owning a token can reveal a secret URL, which can push readers toward minting. The secret URL could be the accompanying source code for […]

Crypto react typescript web3

How to use web3-react

Tutorial about how to use web3-react and hardhat to read and execute Solidity contracts.

Crypto hardhat

How to use ethereum-multicall on a local hardhat node

ethers-multicall actually uses MakerDAO multicall contracts for multicall functionality. On a local chain this contract is not deployed, therefore the request fails with To fix this issue, the MakerDAO-s multicall contract needs to be deployed on the local node. Copy the Multicall.sol contract to your local project. The contract is available in MakerDAO repository Add […]

typescript Uncategorized

vscode-jest doesn’t work for a react app in a yarn workspace/monorepo

I have created a simple yarn workspace with a single package. This package is the default CRA Typescript app. Repository code is on Github. In this repo: Jest works in command line (yarn workspace frontend test) Jest doesn’t work when clicking the button in vscode or on startup. Tests fail with: I can fix the […]


How to transfer a DynamoDB table from one account to another?

This can be done with AWS Glue and IAM roles. Let’s assume we are transferring from account A to account B. Define a role in A to add B as trusted entity to read from DynamoDB. Create the role for AWS account, Another AWS account, and use the account B id. Result is similar to […]