Practical Guide to Fp-ts P2: Option, Map, Flatten, Chain

I'm trying to go along with this and I think I'm stuck I really don't know much about functional programming but this

pipe(
  undefined,
  O.fromNullable,
  O.map(({ bar }) => bar)
);

returns a ts error of cannot find name O I would like to know what I'm doing wrong? is there something I'm missing or didn't import to use the options?

Nice guide!

Just wanted to say that the final example can be simplified a bit. O.map and O.fromNullable can be replaced with a single function: O.fromNullable.

pipe(
  foo,
  O.fromNullable,
  O.chain(O.fromNullableK(({bar}) => bar)),
  O.chain(O.fromNullableK(({buzz}) => buzz))
)

TS playground

Awesome

Very useful, awesome.