feat: add if/else blocks

if now guards a { } block or bare statement with an optional else (and
now else-if chaining). The branch body becomes a statement list; a bare
guarded statement is a list of length one.

1 files changed, 17 insertions, 1 deletions

diff --git a/docs/language.md b/docs/language.md
index d77ca72..4de054f 100644
--- a/docs/language.md
+++ b/docs/language.md
@@ -118,13 +118,29 @@ rax = rbx * rcx     // + - * / % in a value; / % and their = forms use rax:rdx
 rdx = buffer + 31   // address math
 loop:               // label
 goto loop
-if rcx != 0         // == != < <= > >= ; runs the next statement only
+if rcx != 0         // == != < <= > >= ; guards the next statement or a { block }
     goto loop
 syscall
 print_number(r12)   // call; args go into the callee's parameter registers
 stack buf[Point.size] // stack buffer (size is any constant); buf is its base address
 ```
 
+## Branching (`if` / `else`)
+
+`if <expr> <cmp> <expr>` guards either the single next statement or a `{ }` block, and an optional `else` takes its own statement or block. `else if` chains because the `else` body is itself a statement. Comparisons are `==` `!=` `<` `<=` `>` `>=`; a float compare needs an `xmm` register on the left (see [Floating point](#floating-point)).
+
+```hdass
+if rax > rbx
+{
+    rdi = 1
+    goto done
+}
+else if rax == rbx
+    rdi = 0
+else
+    rdi = 2
+```
+
 ## Dereference (`^`)
 
 `^reg` is the memory at the address in `reg` — NASM's `[reg]`. On the left of `=` it stores there. The store width comes from the value operand, so a sized sub-register picks the size: