Fix total pattern match verification

[scheme.git] / abi.md

diff --git a/abi.md b/abi.md
index 5f09227ae56f2b21e31e7eca856a2e9917f60eec..0dbbcc4942b21515229a11ad8f1945f1c22163a6 100644 (file)
--- a/abi.md
+++ b/abi.md
@@ -4,6 +4,22 @@ a heap is allocated at the start, and the address to the next free
 space on it is stored in `heap_start`. it needs to be
 updated/decremented whenever you put anything on the heap
 
+## todo
+- how should allocation be managed?
+make free blocks a doubly linked list. (how big is a block?)
+when allocating, use first free block, move up free pointer
+when freeing, do ???
+
+
+# ownership
+
+```
+(let ([s "hello"])  <- s should be a linear string
+  (mkpair
+    (lambda () (print s))               <- two references to s?
+    (lambda () (print (reverse s)))))
+```
+
 # closures
 
 * lambda: actual function containing the code
@@ -19,6 +35,19 @@ lambda code  1st        2nd       3rd
 address      captive    captive   captive   ...
 ```
 
+## note on recursive closures
+
+The following example shows a recursive lambda, that results in a
+closure that captures itself.
+```
+(let ([f (closure lambda0 (f))])
+  (f 42))
+```
+When this happens, `codegen-let` will insert `(f . 'self-captive)`
+into the environment when codegen'ing the closure. `codegen-closure`
+will then pick this up, and use it to insert its own heap address into
+its inner environment.
+
 # lambdas
 
 lambdas use the system v amd64 calling convention.
@@ -33,3 +62,8 @@ e.g.
 
 * param 0: pointer to the value of `x`
 * param 1: the value of`y`
+
+# inter-function and stack values
+
+ints, bools and closures are passed around within functions in `%rax`.
+adts are passed on the stack, at whatever stack index the code generation was called with.
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