add part one post

Author: bobzhang

_blogposts/2020-09-23-release-8-3.md

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+---
+author: hongbo
+date: "2020-09-23" 
+previewImg:
+category: compiler
+title: What's new in ReScript 8.3 (Part 1)
+description: |
+---
+
+
+# What's new in ReScript 8.3 (Part 1)
+
+ReScript was called BuckleScript, 
+it's a soundly typed language with an optimizing compiler focused on JS platform. 
+It's focused on type safety, performance and JS interop.
+
+[email protected] is available, people can try it via
+
+```
+npm i [email protected]
+```
+
+The changes are listed [here](https://github.com/rescript-lang/rescript-compiler/blob/master/Changes.md#83), this is a large release,  and we will go through some highlighted changes.
+
+
+
+## Lightweight FFI attributes without `bs.` prefix
+
+In this release, we make it optional to have `bs.` prefix it or not, this will make the FFI less verbose,
+
+For example, the old externals for `readFileAsUtf8Sync` used to be written like this
+
+
+```ocaml
+external readFileAsUtf8Sync : string -> (_[@bs.as "utf8"]) -> string = "readFileSync" [@@bs.val] [@@bs.module "fs"]
+```
+
+Could be simplified as 
+```ocaml
+external readFileAsUtf8Sync : string -> (_[@as "utf8"]) -> string = "readFileSync" 
+[@@val] [@@module "fs"]
+```
+
+Note almost all previous attributes with `bs.xx` can be simplified as `xx`, except such two that 
+we don't provide abbreviations:
+
+- `bs.send.pipe` : this attribute was deprecated in favor of `bs.send`, you can still use the long one for backward compatibility.
+
+- `bs.splice` : this attribute was deprecated in favor of `bs.variadic`, you can still use the existing one for 
+backward compatibility.
+
+
+## default import in Es6 support
+
+If you use es6 module output, the default bindings will be compiled properly now:
+
+```ocaml
+external input : string -> string = "default" [@@module "hello"]
+
+let a = input "hello"
+```
+
+Will now be compiled properly under es6 format as below:
+
+```js
+import Hello from "hello";
+var a = Hello("hello");
+```
+
+
+## Customized js file extension support
+
+Now user can pick up their js file extension support per module format:
+
+```json
+  "package-specs": [{
+    "module": "es6",
+    "suffix": ".mjs"
+  },{
+    "module": "commonjs",
+    "suffix": ".cjs"
+  }],
+  
+```
+
+## More flexible filename support
+
+To have better integration with other [JS infrastructures](https://github.com/rescript-lang/rescript-compiler/issues/4624), for example, Next.js/React Native, we allow file names like `404.res`, `Button.Andriod.res` so that it can just be picked up by those tools
+
+
+
+## Better type based inference for pattern `let {a,b,c} = value`
+
+Previously for such piece of code:
+
+```ocaml
+module N = struct 
+    type t = {
+        x : int 
+    }
+end
+
+let f (u : N.t) = 
+    let {x } = u in x + 1 (* type error *)
+```
+
+You will get a type error
+
+```
+Error: Unbound record field x
+```
+
+However, since the compiler already knows the type of `u`, it is capable of looking up label `x` properly, 
+in this release, we make such style work out of the box without adding a module prefix like `let {N.x} = ..`
+
+## Build system enhancement 
+
+A lot of work is put in improving the build system, we will expand on this topic in the next post!
+
+Happy Hacking!