sanctuary-js/sanctuary

Refuge from unsafe JavaScript

David Chambers

@davidchambers

True. We just need chain rather than map if the underlying ADT is sound.

We also need functions that return Maybe a rather than a | Null | Undefined.

The good news is that this is exactly the sort of problem Sanctuary was designed to solve!

@silly-goat

S.get

silly-goat

@silly-goat

get :: (Any -> Boolean) -> String -> a -> Maybe b

David Chambers

@davidchambers

This allows us to interact with user-provided data in a principled way.

@silly-goat

S.get (S.is ($.Array ($.Integer))) ('foo') ({foo: [1, 2, 3]})

silly-goat

@silly-goat

Just ([1, 2, 3])

David Chambers

@davidchambers

@silly-goat

S.get (S.is ($.Array ($.Integer))) ('foo') ({foo: [0, 0.5, 1]})

silly-goat

@silly-goat

Nothing

David Chambers

@davidchambers

@silly-goat

S.get (S.is ($.Array ($.Integer))) ('foo') ({})

silly-goat

@silly-goat

Nothing

David Chambers

@davidchambers

There is also a “plural” version, S.gets, which performs nested lookups.

@silly-goat

S.gets (S.is ($.Array ($.Integer)))
       (['foo', 'bar', 'baz'])
       ({foo: {bar: {baz: [1, 2, 3]}}})

silly-goat

@silly-goat

Just ([1, 2, 3])

David Chambers

@davidchambers

I just used map (map (map (map (f)))) to transform strings inside arrays inside a string map inside a pair inside an either. Living the dream!

Álvaro Touzón

@kasselTrankos

jajajaja

Brad Compton (he/him)

@Bradcomp

:laughing: ]

Ben Briggs

@ben-eb

mega map

Asad Saeeduddin

@masaeedu

you should map your maps over your maps to get a more mappy map

@silly-goat

const mappymap = S.map(S.map)(S.map)
mappymap(x => x * 2)([{ foo: 1 }, { bar: 2 }])

silly-goat

@silly-goat

[{"foo": 2}, {"bar": 4}]

Ben Briggs

@ben-eb

I had three levels of mapping today, Future [Object], not quite hit 4 levels yet :wink:

David Chambers

@davidchambers

Nice one, @ben-eb. :)

I like that, @masaeedu!

plaid/transcribe#27 includes this code:

const map2 = B (map) (map);
const map3 = B (map) (map2);
const map4 = B (map) (map3);

It clearly should have involved map (map) (map), though. :joy:

Ben Briggs

@ben-eb

Yeah, kind of slow going at the moment so I decided to start learning/using Fluture properly :smiley:

David Chambers

@davidchambers

That's an excellent way to make use of a slow period at work.

Ben Briggs

@ben-eb

I really like it. I have done some experiments in the past but making it work on real projects makes a world of difference

David Chambers

@davidchambers

Not having to reason about promises will be wonderful.

Ben Briggs

@ben-eb

I think I'll probably still have promises in the code? But I'd like to start promoting ways of writing lambdas that promisify a fluture composition

const app = pipe([futureF, futureG, ... ]);

const handler = async (event) => app(event).promise();

If there's better ways of doing it though I'm definitely open to ideas

I think for cloud computing we need either a promise or a callback function to let the system know we finished with our lambda

Ben Briggs

@ben-eb

But at least that way I can contain the promises to one specific place

Brad Compton (he/him)

@Bradcomp

That seems like a good plan

Ben Briggs

@ben-eb

Thanks, yeah I hope so :smile:

David Chambers

@davidchambers

@silly-goat

var map = S.map;

//  map4 :: (Functor f, Functor g, Functor h, Functor i) => (a -> b) -> f (g (h (i a))) -> f (g (h (i b)))
var map4 = map (map) (map (map) (map (map) (map)));

map4 (S.toUpper) (S.Right (S.Pair (42) ({x: ['foo'], y: ['bar', 'baz']})));

silly-goat

@silly-goat

Right (Pair (42) ({"x": ["FOO"], "y": ["BAR", "BAZ"]}))

David Chambers

@davidchambers

:point_up: Credit to Asad for this beauty!

Ben Briggs

@ben-eb

Anyone else get cross-eyed looking at that? :smiley:

Although the type signature helps a lot

Ben Briggs

@ben-eb

Looking at it again, should (a -> b) come first in the signature?

Ohhhh. I missed the fat arrow :D

Been a long day

David Chambers

@davidchambers

No worries. It's a long signature. :D

Asad Saeeduddin

@masaeedu

i'm not sure "credit" is the right word :sweat_smile:

it makes for a good brain teaser though

it seems like the more functional programming i learn the less names i use for things

so many things are map

Where communities thrive

People

Repo info

Activity