Folktale 2.3

Folktale 2.3 is officially released~ 🎉🎉🎉

You can now install it as the latest release:

npm install folktale

You can upgrade by specifying the version:

npm install folktale@2.3.0

Not a very exciting release as it mostly just cleans up a few things. But it does promote the Future, Conversions, Lambda, Fantasy-Land, Result, and Validation APIs to stable at last. Tasks are still in need of some love before they can reach that status, although hopefully most of the edge cases in the API have been fixed now.

This release improves the error reporting in the ADT APIs as well. Previously if you forgot to provide one of the cases to an union’s matchWith method, you’d get this very unhelpful message:

const { union } = require('folktale@2.1.0/adt/union');
const Optional = union('optional', {
  Some(value) { return { value } },
  None() { return {} }
});

function getValue(optional) {
  return optional.matchWith({
    Some(value) { return value }
  });
}

getValue(Optional.Some(1));  // => 1
getValue(Optional.None());   // => TypeError: pattern[name] is not a function

In Folktale 2.3 you get a more descriptive error message:

Error: Variant "None" is not covered in pattern.
This could mean you did not include all variants in 
your Union's matchWith function.

For example, if you had this Union:

const Operation = union({
  Add: (a, b) => ({ a, b }),
  Subtract: (a, b) => ({ a, b }),
})

But wrote this matchWith:

op.matchWith({
  Add: ({ a, b }) => a + b
  // Subtract not implemented!
})

It would throw this error because we need to check against 'Subtract'. 
Check your matchWith function's argument, it's possibly missing the 
'None' method in the object you've passed.

We also support a “match anything” special value now. So another way of writing the getValue function above that would be more practical for unions with many cases would be:

const { union } = require('folktale/adt/union');

const Optional = union('optional', {
  Some(value) { return { value } },
  None() { return {} }
});

function getValue(optional) {
  return optional.matchWith({
    Some(value) { return value },
    [union.any]() { return null }
  });
}

getValue(Optional.Some(1));  // => 1
getValue(Optional.None());   // => null

Check out the changelog for all the changes

Acknowledgements

As always, a huge thank you to everyone who contributed to improving Folktale, by reporting errors, sending feedback, talking about it, sending patches, etc.

This release wouldn’t be possible without the contributions of @Josh-Miller, @JesterXL, @andys8, and @pernas. Really, thank you :>

(Read more)

Using release channels in a better way

Hello~

When Folktale 2 was released last year two release channels were defined:

• latest for the stable and tested versions;
• next for the stable, but not tested versions;

But now: where do we put experimental branches (like the TypeScript typings one) and limited test releases so users can check if problems are fixed before we merge a PR? There wasn’t really a place for them, and this led to some mess in the releases.

So, from now on, Folktale will be using temporary channels for these cases. A temporary channel is a sequence of releases associated with a tag that we expect to either merge back into the master (so it becomes a next release), or die. These tags will likely end up being similar to the name of the branch in the PR, but shorter.

The TypeScript typings experimental branch (feat/typescript-typings) will be the first to use this scheme, using the tag tstypes.

(Read more)

Folktale 2.1 and TypeScript Support

Hello everyone~

I had this release planned for just before New Year’s but I wasn’t feeling well so that didn’t happen.

Anyway. There are two releases today: Folktale 2.1, and some experimental TypeScript support in the next release, Folktale 3.x.

(Read more)