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@@ -1,8 +1,6 @@ -% Cute scheme design overview -% Rose Hogenson; Cute scheme development team -% April 22, 2022 +# Cute Scheme -# Background +## Background Scheme is a simple language, and has a number of open specifications. These two qualities make it a popular target for hobby compilers. The @@ -15,13 +13,13 @@ runtime. For a program that uses eval, it will by necessity need to have the full compiler bundled as part of the runtime. My goal is to write a self-hosting scheme compiler targeting a minimal bytecode. -# Objective +## Objective Cute scheme is a partial r7rs implementation with a focus on ease of implementation and a reusable library. The frontend is written in r7rs Scheme, and compiles to a minimal bytecode. -# Detailed design +## Detailed design The cute scheme compiler (like most compilers) consists of a number of phases that gradually transform a program from scheme code through @@ -29,7 +27,7 @@ numerous intermediate representations. The csc compiler has 2 such intermediate representations, not counting bytecode itself. These two languages are called IR1 and IR2. -## IR1 +### IR1 IR1 can be thought of as scheme code with all the macros expanded. An IR1 program or library is a tree structure composed of one of a few @@ -172,7 +170,7 @@ The builtin forms of IR1 are described below. And that's all the IR1 types. The design of the macro expander is sketched briefly below. -## Macro expansion +### Macro expansion Macro expansion essentially consists of a compiler from scheme code to IR1. As the compiler walks the input scheme expression, it holds an @@ -190,8 +188,6 @@ expression doesn't look like a macro invocation, it could be a procedure call, a constant, or a variable reference. Either way it will get compiled to the corresponding IR1 construct. -### Syntax-rules - The `syntax-rules` syntax transformer takes as input a `syntax-rules` form, and the output is a syntax transformer. Recall that a syntax transformer accepts a scheme expression and emits IR1. In this way, @@ -306,7 +302,7 @@ variable that was in-scope when the macro was defined. It's possible that this behavior isn't quite right for macros that generate other macros, but the above paragraph is breaking my brain. -## IR2 +### IR2 IR2 is what is known as "continuation passing style". When I learned about continuation passing style in school, we learned that it's @@ -343,7 +339,7 @@ The syntax types for IR2 are given below. (continuation call/cc-continuation)) ``` -## IR3 +### IR3 I've only just started thinking about IR3, but it's the closure conversion step for IR2. Afterwards, we will transform all |