Confusion about the correct way to import from fp-ts

[CarstenLeue]

📖 Documentation

I love fp-ts and I appreciate the good documentation. However I think that in most documentation the examples do not illustrate the "correct" way to import from fp-ts.

Example: https://dev.to/gcanti/getting-started-with-fp-ts-monad-6k

The examples show e.g:

import { Option, some, none, option } from 'fp-ts/lib/Option'

On the other hand #1241 has added support for es6 imports that work well with tree shaking. This way of importing leaves the choice to the importing tool what version to consume, the commonjs or the es6 version (which is the recommended way to import). An example is:

import { Option, some, none, option } from 'fp-ts/Option'

When mixing imports however we end up with multiple copies of fp-ts being used. This not only increases the size of the final bundle (if packed), it also breaks the concept of singletons. The constant Option.none e.g. is probably supposed to be a singleton, but we end up with different instances depending on how fp-ts gets imported.
Libraries from the ecosystem address this via a post-processing step using import-path-rewrite which results in a correct result, by explicitly importing from fp-ts/es6 for the es6 case. But this is basically unnecessarily complex, an import directly from fp-ts would work fine both for the es6 and the commonjs case, because of the entries main and modules in the package.json files. For exploiters of fp-ts it is also very easy to get this wrong, since the examples point to the commonjs import style, only.

I suggest to clarify the intended import style in the fp-ts documentation and - if possible - rework the documentation to use the import directly from fp-ts instead of from fp-ts/lib.

[CarstenLeue]

Related: #1003, #1044

[gcanti]

blog posts amended

[luisincrespo]

blog posts amended

@gcanti which blog posts are you referring to? Thanks!

[gcanti]

@luisincrespo https://dev.to/gcanti/series/680

[danielo515]

@luisincrespo https://dev.to/gcanti/series/680

That seems to be only a list of blog posts, and I don't see anything specific to this question. Do you mind a direct link?

[gcanti]

@danielo515 the correct way to import from fp-ts is

import ... from 'fp-ts/<module>'

example with Option:

import * as Option from 'fp-ts/Option'

[danielo515]

That was my intuition, thanks for confirming. There are, however, a lot of code examples wirh the other style of imports. I think it will be useful to add a statement about this in the code conventions section. El mar, 24 oct 2023, 18:06, Giulio Canti ***@***.***> escribió:

…

@danielo515 <https://github.com/danielo515> the correct way to import from fp-ts is import ... from 'fp-ts/<module>' example with Option: import * as Option from 'fp-ts/Option' — Reply to this email directly, view it on GitHub <#1606 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AARKJWO5JX7F7TSWGNTULBTYA7RP7AVCNFSM5GQA76UKU5DIOJSWCZC7NNSXTN2JONZXKZKDN5WW2ZLOOQ5TCNZXG42TMMBSGY4Q> . You are receiving this because you were mentioned.Message ID: ***@***.***>

[gcanti]

@danielo515 in the src folder I found these #1913, are there others?

[danielo515]

Yes, years of medium (and similar) introductory articles to fp-ts: https://www.thisdot.co/blog/functional-programming-in-typescript-using-the-fp-ts-library-deep-dive-into/ https://hvalls.dev/posts/intro-functional-fpts https://zanza00.gitbook.io/learn-fp-ts/either ***@***.***/fp-ts-for-the-impatient-ad6c0a9a257b And other docs in the ecosystem: https://github.com/gcanti/fp-ts-local-storage https://github.com/gcanti/fp-ts-laws El mar, 24 oct 2023, 18:53, Giulio Canti ***@***.***> escribió:

…

@danielo515 <https://github.com/danielo515> in the src folder I found these #1913 <#1913>, are there others? — Reply to this email directly, view it on GitHub <#1606 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AARKJWPNLXVT2BEZUUK5GIDYA7W65AVCNFSM5GQA76UKU5DIOJSWCZC7NNSXTN2JONZXKZKDN5WW2ZLOOQ5TCNZXG43DINBVGEZQ> . You are receiving this because you were mentioned.Message ID: ***@***.***>