This is a binding to embed the Wren language into Crystal and call Wren code from Crystal and viceversa.
Wren is a small, fast, class-based, concurrent scripting language.
I like the syntax much better than Lua's or Javascript's and it's a fairly powerful language with decent performance.
This is a WIP, I may end up vendoring wren inside this project.
-
Install wren as a library in your system.
- In Arch:
yay install wren - In other systems: Embedding instructionshtml#embed-the-vm
- In Arch:
-
Add the dependency to your
shard.yml:dependencies: cr-wren: github: ralsina/cr-wren
-
Run
shards install
This is a fully commented example:
require "../src/wren.cr" # Adjust as needed
vm = Wren::VM.new "myvm"
# We can just tell the VM to interpret (run) code
vm.interpret "main", "System.print(\"Hello World!\")"
# This defines a function in Wren
vm.interpret "main", %(
var add = Fn.new { |a,b|
return a+b
}
)
# And we can call it from Crystal
puts vm.call("main", "add", "call", [1, 2]) # => 3.0
puts vm.call("main", "add", "call", ["1", "2"]) # => "12"
# This fails with a runtime error even when the equivalent Wren code works
# probably a bug somewhere
# puts vm.call("main", "add", "call", [[1, 2], [3, 4]]) # => [1,2,3,4]
# Register a Crystal proc to add floats into the Wren VM
vm.register_function(
"main", "Math", "add",
Wren::VM.wrap("myvm", ->(a : Float64, b : Float64) : Float64 {
a + b
})
)
# Register a proc to add 3 floats. We can register the same proc more than
# once with the same name and different arity
vm.register_function(
"main", "Math", "add",
Wren::VM.wrap("myvm", ->(a : Float64, b : Float64, c : Float64) : Float64 {
a + b + c
})
)
# We also need to declare it as "foreign" in Wren.
vm.interpret "main", %(
class Math {
foreign static add(a,b)
foreign static add(a,b,c)
}
)
# And we can call it on Wren, which will use the Crystal code
vm.interpret "main", %(
System.print("2+3.5=")
System.print(Math.add(2,3.5))
System.print("1+2+3=")
// We can pass a string as argument here because cr-wren will cast it to Float64
System.print(Math.add("1",2,3))
) # 2+3.5=5.5 ¨1"+2+3=6This is early code, not much here.
- Fork it (https://github.com/ralsina/cr-wren/fork)
- Create your feature branch (
git checkout -b my-new-feature) - Commit your changes (
git commit -am 'Add some feature') - Push to the branch (
git push origin my-new-feature) - Create a new Pull Request
- Roberto Alsina - creator and maintainer