Fowltalk is a little prototype-based programming language.

Interpreter Status

• ✅ record stack effect of opcodes during building
• ✅ implement non-local return for blocks
• 📝 implement image saving/loading
• ✅ implement test runner
• ✅ unhandled messages send 'unknownMessage:withArguments:'
• 📝 add a logging library, more than just ft_debug()
• 📝 implement a garbage collector

Virtual Machine

The VM is a simple stack machine with 8 instructions

• literal index - load literal onto the stack
• send argc - pop a selector and argc arguments from the stack and invoke the selector on the arguments (receiver is argument #0)
• self-send argc - pop a selector and argc arguments from the stack and invoke the selector on the current activation context
• return contexts - return through context activation contexts
• init-slot index - initialize a slot
• pop count - pop count from the stack
• push-context - push a special object onto the stack
• extend arg - extend the argument to the next opcode

Primitives

• __VTable_instantiate -

• __Object_clone - return a shallow clone of the receiver

• __Object_respondsTo: - return a boolean for whether or

• __Object_copyAddingSlot:value:

• __Object_copyRemovingSlot:

• __Object_updateSlot:value: -

• __Object_fetchSlot: - fetch a slot value without evaluating it

• __Object_addStaticSlot:value: - copy the vtable and add a static slot

• __Object_vtable - fetch the vtable for an object

• __String_concat: - join two strings in a new copy

• __String_print - print out the receiver to stdout

• __String_printLn - print out the string and a newline to stdout

• __String_readFile - treat the receiver as a filename and read the contents

• __String_compileAnonymousMethod - treating the receiver as Fowltalk source code, compile into an anonymous method

• __Integer_add:, __Integer_subtract:, __Integer_multiply:, __Integer_divide: - math operations for integers

• __Integer_print, __Integer_printLn - printing functions for integers

• __VM_activateMethodContext - switch to the receiver as a method context in the current vm