Draft: let? blog post

[fhammerschmidt]

Closes #1086

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[cristianoc]

Assistant:

Coming from other languages:

Rust developers will immediately recognize and appreciate it
JavaScript/TypeScript developers might find it unfamiliar but useful
Functional programming advocates may prefer more general monadic solutions

Overall Prediction
I think this will be well-received once people try it. The ReScript community generally values pragmatism alongside functional programming principles, and this strikes a good balance. The experimental flag is smart - it gives the team room to iterate based on real usage patterns.
The main debates will likely center around:

Whether to expand beyond built-ins to custom variants
Syntax bikeshedding (though let? is quite good)
Integration with future language features

This feels like a natural evolution for ReScript - maintaining its OCaml roots while improving developer experience for common patterns.

looks spot on to me

[cristianoc]

Areas for Improvement
Structure and flow: The post jumps between concepts without clear transitions. The section about "two observations" feels disconnected from what follows, and the explanation of how it works could be better integrated.
Terminology inconsistency: The post uses "let-unwrap," "let?," and "unwrap syntax" interchangeably without establishing clear naming conventions upfront.
Technical precision: Some statements could be clearer:

"matches the explicitness of ReScript we all like" - what does this mean exactly?
"plays nicely with async/await" - how specifically?
The distinction between block/local vs top-level usage needs clarification
"And it is for block or local bindings only; top-level usage is rejected" - why this restriction?

Suggested Improvements

Lead with a clear definition of what let? does before showing examples
Structure as problem → solution → implementation rather than jumping between topics
Standardize terminology early and stick with it
Add clearer section breaks to help readers follow the flow
Expand on the restrictions - explain why certain limitations exist
Include error cases in examples to show the full picture

Seems legit, except the last suggestion might be too much

[cristianoc]

Btw let? is great balanced design. Nice one @zth

[nojaf]

Maybe add a link to https://rescript-lang.org/docs/manual/v12.0.0/api/stdlib/result#value-flatMapOkAsync

[nojaf]

This looks good and I think it’s ready to go.

One feeling I still get is that it reads like a new idea we haven't really tested in our codebase. I'm not sure if that's an issue or worth mentioning, but it's hard to tell whether this will be game-changing or not.