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TylorS / snabbdom-selector

CSS Selectors for Snabbdom Virtual Nodes
MIT License
32 stars 7 forks source link

curry2 being called inside the index makes it not tree-shakeable #25

Closed Sinewyk closed 6 years ago

Sinewyk commented 7 years ago

That pulls everything (through, readable stream, process, Buffer, etc) various module bundlers, whether you have tree shaking activated or not.

Context: just updating from @cycle/dom 19.2.0 to 19.3.0, which updated snabbdom-selector from 1 to 2, and updated the manner of the import https://github.com/cyclejs/cyclejs/commit/7af2b198269c3d480d64ab7a5e151ca7a161a967#diff-bba593365d0d8866a7ba95bfd04dd4a0R3 "broke" this.

Many way to fix it I suppose. Just don't call curry2 in the index and instead curry inside findMatches ? Split files again ?

Sinewyk commented 7 years ago

Edit: No apparently moving the curry2 function call inside the findMatches also does not work. More precisely Side effects in initialization of unused variable select [./node_modules/snabbdom-selector/lib/es6/index.js:3,0] so, nothing gets dropped.

Split again or accept that we may need to somehow mark the function as pure so that tree shaker can do their thing. Probably.

Sinewyk commented 7 years ago

For what's it's worth, some additional info around here https://gitter.im/cyclejs/cyclejs?at=59f2d81fd6c36fca31a16029.

IMO, for @cycle/dom we should just export what's necessary to limit the abusive bundling and require just that in @cycle/dom itself

TylorS commented 7 years ago

It is possible to tackle this via tooling, we've had the same discussion in the most.js issues https://github.com/mostjs/core/issues/138 with an (still open) accompanying PR here: https://github.com/mostjs/core/pull/143.

Effectively it uses babel and a plugin babel-plugin-annotate-pure-calls which allows uglifyjs to know that a function is pure when it otherwise assumes it is impure which helps greatly with tree-shaking.

Sinewyk commented 7 years ago

I've tried manually tagging so that

export const select = curry2(findMatches)

becomes

export const select = /*@__PURE__*/curry2(findMatches)

It did not help even though I saw the dropping PURE call or something in the warnings.

Andarist commented 6 years ago

@Sinewyk could you share a repro? I've investigated those issues quite a bit and might be able to help identify the problem