Curry, code, and databases

Ben Doty — Tue, 02 Mar 2021 02:56:39 +0000

You may have heard of curry, it's a type of food. People eat curry, and they may or may not like it. There is also a concept in programming called currying, and there is a lot to like about it.

The curry part

A curried function is a function that uses partial functions as it's arguments. It's a large part of functional programming and allows for better composition of software.

Here is an example

const add = a => b => a + b;

You may notice that there are two arrow functions. That is how you curry. You take the first parameter, a, and it creates a partial function that is used as an argument for the second parameter b.

These are functionally equivalent:

// Curried add
const add = a => b => a + b;

// Regular add
const add = (a,b) => a + b;

However, the curried version is a lot more diverse because of the partial function it creates.

const add = a => b => a + b;

add(1) // --> function
add(1)(2) // --> 3

// The first function is called, a partial function is created, 
// and then it's passed to the second for the final calculation.

We can use that partial function to create "presets".

// Create preset using curried add function above
const add5 = add(5); // Partial function with 5 stored as variable 'a'

const add5(5) // --> 10

You can start to see how this is powerful.

The database part

A little while ago I made a Mongodb library for my own use because I was annoyed with the default driver. I used currying to create a really simple API and I just released it on NPM for everyone to use.

It's called mongo-curry. It supports ES6 syntax, is super easy to test, and is just a really nice little library

If you want to try it, you can install it with

npm install mongo-curry

yarn add mongo-curry

Of course you need to know how to use it, so here is the docs

The last part

I hope you found something here helpful.

If you have some ideas on how to improve either the documentation, or the library, or would like to hear more about functional JavaScript please let me know.

Writing and publishing the library and documentation took a couple weeks worth of work. If you find it helpful and would like to see me make more stuff you can buy me a coffee

GraphQL + TypeScript - What I've Found

Ben Doty — Wed, 09 Sep 2020 16:25:43 +0000

I've been working on an application recently where I have decided to use TypeScript with ApolloServer. It's a microservice architecture, so Apollo's Federation works great for me. However, despite being written in TypeScript, Apollo just absolutely struggles to use it. Now, it could be me, I've never used this combination before, but it seems to me that Apollo just doesn't have the developer experience it should, in TypeScript at least.

I've used Apollo multiple times in my projects, it always has worked fine, until now. Now, I still really like Apollo and will continue to use it. However, let me explain just how frustrating it is to use it with TypeScript.

beginIncrediblyFrustratingExperience():

Hey there! I see you are using TypeScript! This is great. Go ahead and set up your project like normal. Whoops, resolvers don't work right. You need IndexedString that takes an IResolver type that you get from the graphql-tools library.
Also, the IndexedString needs a custom definition.

So now you need a special interface that goes into a type that allows you to pass in the IResolvers. Implement all that, excellent it works.

Now you want to actually implement the resolvers? Great! Let's do that like normal except that every single parameter needs a type. Well, that makes sense except, I DON'T KNOW WHAT THAT TYPE IS! Okay, so we will just mark it as any. Bad practice but it works so let's move on. I'm on the clock here okay?

Now you want custom directives? Nope you can't have them because they require special types as well apparently. Also they don't just go in your federatedSchema, you have to create two schemas and merge them.

What's that? Your special types can't be found? Wonderful. The day just got better. Oh, and tests? Don't even bother with those. They will ruin your day. Write those in plain JavaScript or you'll have an aneurysm.

endStory()

I guess this is a bit of a rant because I've been working on this for days now and I have almost nothing to show for it. It's incredibly frustrating, but I also wanted to raise a little awareness of this issue. Now, like I said, I haven't tried this combination before. I've used both TypeScript and Apollo, but never together. I could be missing something somewhere. But from what I see, people have been opening issues and complaining about this in the repository. I'm curious if any of you have managed to find their way through this particular swamp. If you have, please direct me toward some resources I can use. Otherwise, I may just drop TypeScript all together. (I really don't want to if I don't have to). Anyway, thanks for taking the time to read this. I hope your journey is easier than mine.

DEV Community: Ben Doty

Curry, code, and databases

The curry part

The database part

The last part

GraphQL + TypeScript - What I've Found