cea71c2fe4
The previous GC implementation used a recursive mark method. This can result in stack overflows when attempting to mark deeply nested objects. This commit replaces the recursive approach with an iteritive one, moving the state stack from the C call stack to the `WrenVM` structure. As objects are 'grayed' they are pushed onto the VM's gray stack. When we have grayed all of the root objects we iterate until the stack is empty graying any obejcts which haven't been marked as dark before. At the end of the process we clean up all unmarked objects as before. This commit also adds a few new tests which check garbage collection by allocating some new deeply nested objects and triggering the GC a few times in the process.
Wren is a small, fast, class-based concurrent scripting language
Think Smalltalk in a Lua-sized package with a dash of Erlang and wrapped up in a familiar, modern syntax.
System.print("Hello, world!")
class Wren {
flyTo(city) {
System.print("Flying to ", city)
}
}
var adjectives = Fiber.new {
["small", "clean", "fast"].each {|word| Fiber.yield(word) }
}
while (!adjectives.isDone) System.print(adjectives.call())
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Wren is small. The VM implementation is under 4,000 semicolons. You can skim the whole thing in an afternoon. It's small, but not dense. It is readable and lovingly-commented.
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Wren is fast. A fast single-pass compiler to tight bytecode, and a compact object representation help Wren compete with other dynamic languages.
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Wren is class-based. There are lots of scripting languages out there, but many have unusual or non-existent object models. Wren places classes front and center.
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Wren is concurrent. Lightweight fibers are core to the execution model and let you organize your program into an army of communicating coroutines.
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Wren is a scripting language. Wren is intended for embedding in applications. It has no dependencies, a small standard library, and an easy-to-use C API. It compiles cleanly as C99, C++98 or anything later.
If you like the sound of this, let's get started. You can even try it in your browser! Excited? Well, come on and get involved!
