feat: if

README.md

@@ -24,12 +24,16 @@ Hello, World!
 DONE:
 - Parsing, Compiling, Running(VM)
 - Intrinsic:
-  - `fun`, `do`, `print`
-  - Math:
+  - `fun`, `do`, `print`, `if`
+  - Math: 
+    - `+` , `add`
+    - `-` , `sub`
+    - `*` , `mul`
+    - `/` , `div`
 
 TODO:
 - Prove turing complete
 - Do the intrinsic left
 - Quote, Quasiquote, etc.
 - Optimizing
-- Remove unnecessary copying in the entire codebase
+- Remove unnecessary copying in the entire codebase (also with `.unwrap()`)

blspc/src/compiler/compile.rs

@@ -49,6 +49,18 @@ impl Compiler {
                                     result.append(&mut self.compile(body.clone())?);
                                     result.push(Instr::Return);
                                 },
+                                "if" => {
+                                    let mut cond = self.compile(cdr[0].clone())?;
+                                    result.append(&mut cond);
+
+                                    let mut then = self.compile(cdr[1].clone())?;
+                                    let mut else_ = self.compile(cdr[2].clone())?;
+
+                                    result.push(Instr::JumpIfFalse { to: then.len() + 1}); // +1 for the jump instr
+                                    result.append(&mut then);
+                                    result.push(Instr::Jump { to: else_.len() });
+                                    result.append(&mut else_);
+                                }
                                 _ => {
                                     result.append(&mut self.compile_intrinsic(call, &cdr)?);
                                 }
@@ -72,8 +84,6 @@ impl Compiler {
         match intrinsic.as_str() {
             "print" => {
                 result.append(&mut self.compile(args[0].clone())?);
-                let to = self.next_register();
-                let call_register = self.next_register();
                 
                 result.push(Instr::Push { value: Type::Int(1) });
                 result.push(Instr::Call);
@@ -141,7 +151,7 @@ impl Compiler {
             },
             Symbol(s) => {
                 result.push(Instr::Comment { text: format!("{} variable", comp) });
-                result.push(Instr::Jump { to: format!("function_{}", s), });
+                result.push(Instr::JumpLabel { to: format!("function_{}", s), });
             },
             _ => { result.append(&mut self.compile(atom.clone())?); }
         }

blspc/src/vm/instr.rs

@@ -189,9 +189,10 @@ pub enum Instr {
     // Stack arithmetic.
     Add, Sub,
     Mul, Div,
-    // Jumping
-    Jump { to: String },
-    PopJumpIfFalse { to: usize },
+    // Jumping.
+    JumpLabel { to: String }, // Jump to (function) label.
+    Jump { to: usize }, // Jump with offset.
+    JumpIfFalse { to: usize },
 
     Return,
 }
@@ -212,8 +213,9 @@ impl Display for Instr {
             Instr::Sub                      => write!(f, "    SUB"),
             Instr::Mul                      => write!(f, "    MUL"),
             Instr::Div                      => write!(f, "    DIV"),
+            Instr::JumpLabel { to }         => write!(f, "    JMPL            {}", to),
             Instr::Jump { to }              => write!(f, "    JMP             {}", to),
-            Instr::PopJumpIfFalse { to }    => write!(f, "    PJMPF           {}", to),
+            Instr::JumpIfFalse { to }       => write!(f, "    JMPF            {}", to),
             Instr::Return                   => write!(f, "    RET"),
         }
     }

blspc/src/vm/parser.rs

@@ -28,7 +28,8 @@ pub fn parse_instr(src: &str) -> Vec<Instr> {
             "SUB"   => { result.push(Instr::Sub); },
             "MUL"   => { result.push(Instr::Mul); },
             "DIV"   => { result.push(Instr::Div); },
-            "JMP"   => { result.push(Instr::Jump { to: tokens[1].to_string() }); },
+            "JMPL"  => { result.push(Instr::JumpLabel { to: tokens[1].to_string() }); },
+            "JMP"   => { result.push(Instr::Jump { to: tokens[1].parse::<usize>().unwrap() }); },
             "PJMPF" => todo!(),
             "RET"   => { result.push(Instr::Return); },
             _ => {

blspc/src/vm/vm.rs

@@ -119,12 +119,16 @@ impl VM {
                     self.push((lhs / rhs)?)?;
                     continue 'tco;
                 },
-                Jump { to } => {
+                JumpLabel { to } => {
                     let pointer = self.get_function_pointer(to.to_string())?;
                     self.jumped_from = self.instr_pointer;
                     self.instr_pointer = pointer;
                     continue 'tco;
                 },
+                Jump { to } => {
+                    self.instr_pointer += *to as isize + 1;
+                    continue 'tco;
+                },
                 Return => {
                     if self.jumped_from == 0 { return Ok(()); }
                     self.instr_pointer = self.jumped_from;

example/if.blsp

@@ -1,3 +1,4 @@
-(if true
-    (print (+ 34 35))
-    (print "False"))
+(fun main
+    (if true
+        (print "True")
+        (print "False")))