Failed to import - io-ts

[MichaelHirn]

Failing module

• GitHub: https://github.com/gcanti/io-ts
• npm: https://www.npmjs.com/package/io-ts

import { something } from 'https://esm.sh/io-ts@v2.2.16?target=deno'

and

import { something } from 'https://esm.sh/io-ts@v2.2.16?target=deno&deps=fp-ts@2.11.8'

Error message

After running deno run I got this:

TS2344 [ERROR]: Type 'string' does not satisfy the constraint 'never'.
    at https://cdn.esm.sh/v68/fp-ts@2.2.0/lib/Either~.d.ts:305:155

Found 33 errors.

The important part is, that it tries to load fp-ts with version 2.2.0, even though io-ts species in peerDependencies that at least fp-ts@2.5.0 should be used. I have no idea where 2.2.0 is coming from (even when deps=fp-ts@2.11.8 is specified) and this is probably causing all the TS2344 errors.

Additional info

Also interesting to note is that, if I try to run with no-check flag:

export type { Branded } from 'https://esm.sh/io-ts@v2.2.16?target=deno&no-check'

the errors disappear but the exported types seem to disappear as well and I get this when running deno run:

error: TS2724 [ERROR]: '"https://esm.sh/io-ts@v2.2.16?target=deno&no-check"' has no exported member named 'Branded'. Did you mean 'brand'?
export type { Branded } from 'https://esm.sh/io-ts@v2.2.16?target=deno&no-check';

• esm.sh version: 68
• Deno version: 1.19.1

Potentially related issues: #168 #273

[ije]

when you pass the no-check option you can not use import type since there is no dts

[MichaelHirn]

Thanks for your reply, that makes sense with the no-check flag

[MichaelHirn]

any ideas where the fp-ts@2.2.0 is coming from and if I can force it to load a different fp-ts version?

[ije]

i will look into it, not sure what happened yet

[ije]

fixed in v71, i also added the testing here: https://github.com/esm-dev/esm.sh/blob/master/test/deno/io-ts/io-ts.test.ts

[MichaelHirn]

Many thanks @ije. This did fix the problem, however io-ts remains practically unusable for most, due to another error that pops up. I created a repo to reproduce and will open a separate issue