Michael Martin mlms13

any: magic, ill-behaved type that acts like a combination of never (the proper [bottom type]) and unknown (the proper [top type])
- Anything except never is assignable to any, and any is assignable to anything at all.
- Identities: any & AnyTypeExpression = any, any | AnyTypeExpression = any
- Key TypeScript feature that allows for [gradual typing].
unknown: proper, well-behaved [top type]
- Anything at all is assignable to unknown. unknown is only assignable to itself (unknown) and any.
- Identities: unknown & AnyTypeExpression = AnyTypeExpression, unknown | AnyTypeExpression = unknown

Prefer over any whenever possible. Anywhere in well-typed code you're tempted to use any, you probably want unknown.

Thinking Like a Function

Part 1: What's a function?

As a software engineer, you probably think of a function as a unit of code that takes some arguments and returns some value, eg:

 function square(x) { 
   return x * x;
 }

A vision for data interchange in Elm

How do you send information between clients and servers? What format should that information be in? What happens when the server changes the format, but the client has not been updated yet? What happens when the server changes the format, but the database cannot be updated?

These are difficult questions. It is not just about picking a format, but rather picking a format that can evolve as your application evolves.

Literature Review

By now there are many approaches to communicating between client and server. These approaches tend to be known within specific companies and language communities, but the techniques do not cross borders. I will outline JSON, ProtoBuf, and GraphQL here so we can learn from them all.

	module AsyncResult = Relude.AsyncResult;
	module Effect = ReludeReact.Effect;
	module IO = Relude.IO;
	module Option = Relude.Option;
	module Reducer = ReludeReact.Reducer;

	let (toBusy, completeOk, completeError) =
	AsyncResult.(toBusy, completeOk, completeError);

	type state('a, 'e) = AsyncResult.t('a, 'e);

	open Relude.Globals;

	[@bs.module "dotenv"] external getEnvVars: unit => unit = "config";

	let getEnvVars = () =>
	getEnvVars()
	\|> (() => Node.Process.process##env)
	\|> (Js.Dict.map((. x) => x \|> Json.Encode.string) >> Json.Encode.dict);

	type style = ReactDOMRe.Style.t;
	type element = React.element;

	module Breadcrumb = {
	[@bs.module "antd"] [@react.component]
	external make:
	(~ariaLabel: string=?, ~key: string=?, ~style: style=?, ~children: 'b) =>
	element =
	"Breadcrumb";