chore: add lib var for macos usage (#1)

README.md

@@ -1,23 +1,32 @@
 # Extism Lean 4 Host SDK
 
-This repo contains the [Lean 4](https://github.com/leanprover/lean4) package for integrating with [Extism](https://github.com/extism/extism)
+This repo contains the [Lean 4](https://github.com/leanprover/lean4) package for
+integrating with [Extism](https://github.com/extism/extism)
 
-Note: These bindings are under active development and the public API is unstable. 
+Note: These bindings are under active development and the public API is
+unstable.
 
 ## Building
 
-The Extism shared object is required for these bindings to work, see our [installation instructions](https://extism.org/docs/install/).
+The Extism shared object is required for these bindings to work, see our
+[installation instructions](https://extism.org/docs/install/).
 
 From the root of the repository run:
 
 ```sh
 lake build
+
+# on macos
+# DYLD_LIBRARY_PATH=/usr/local/lib lake build
 ```
 
 To run the tests:
 
 ```sh
 lake exe test
+
+# on macos
+# DYLD_LIBRARY_PATH=/usr/local/lib lake exe test
 ```
 
 ## Getting started
@@ -30,11 +39,13 @@ require extism from git "https://github.com/extism/lean4-sdk" @ "main"
 
 ### Loading a Plug-in
 
+The primary concept in Extism is the
+[plug-in](https://extism.org/docs/concepts/plug-in). A plug-in is a code module
+stored in a `.wasm` file.
 
-The primary concept in Extism is the [plug-in](https://extism.org/docs/concepts/plug-in). A plug-in is a code module stored in a `.wasm` file.
-
-Plug-in code can come from a file on disk, object storage or any number of places. Since you may not have one handy, let's load a demo plug-in from the web. Let's
-start by creating a main function that loads a plug-in:
+Plug-in code can come from a file on disk, object storage or any number of
+places. Since you may not have one handy, let's load a demo plug-in from the
+web. Let's start by creating a main function that loads a plug-in:
 
 ```
 import Extism
@@ -48,8 +59,9 @@ def main : IO Unit := do
 
 ### Calling A Plug-in's Exports
 
-This plug-in was written in Rust and it does one thing, it counts vowels in a string. It exposes one "export" function: `count_vowels`. We can call exports using `Plugin::call`.
-Let's add code to call `count_vowels` to our main func:
+This plug-in was written in Rust and it does one thing, it counts vowels in a
+string. It exposes one "export" function: `count_vowels`. We can call exports
+using `Plugin::call`. Let's add code to call `count_vowels` to our main func:
 
 ```
 import Extism
@@ -63,6 +75,6 @@ def main : IO Unit := do
   // => {"count":3,"total":3,"vowels":"aeiouAEIOU"}
 ```
 
-Note: `call` accepts any type that implements `Extism.ToBytes` as input, and returns any type that implements 
-`Extism.FromBytes`, these are implemented for `ByteArray`, `String` and `Lean.Json a`
-
+Note: `call` accepts any type that implements `Extism.ToBytes` as input, and
+returns any type that implements `Extism.FromBytes`, these are implemented for
+`ByteArray`, `String` and `Lean.Json a`