[V-119] While loops (#50)

* Add basic support for while loops

* Update docs

README.md

@@ -15,10 +15,9 @@ pub fn main()
 
 **Disclaimer**
 
-Voyd is in it's very early stages of development. Voyd is not ready for public
-announcement or use. Some core syntax and semantics are subject to change.
-Expect frequent breaking changes. In addition, many documented features are not
-yet implemented.
+Voyd is in it's very early stages of development. Voyd is not ready for production use. Some syntax and semantics are still subject to change. Expect frequent breaking changes.
+
+All features documented in README Overview are fully implemented unless otherwise stated. Features documented in the [reference](./reference/) are not yet marked with status and may not be implemented.
 
 **Features**:
 
@@ -84,9 +83,9 @@ true // Boolean
 false // Boolean
 1 // i32 by default
 1.0 // f64 by default
-"Hello!" // String, can be multiline, supports interpolation via ${}
-[1, 2, 3] // Array literal
-(1, 2, 3) // Tuple literal
+"Hello!" // String, can be multiline, supports interpolation via ${} (NOTE: Not yet implemented)
+[1, 2, 3] // Array literal (NOTE: Not yet implemented)
+(1, 2, 3) // Tuple literal  (NOTE: Not yet implemented)
 {x: 2, y: 4} // Structural object literal
 ```
 
@@ -130,7 +129,7 @@ Voyd also supports uniform function call syntax (UFCS), allowing functions to be
 
 ### Labeled arguments
 
-Status: Not yet implemented
+> Status: Not yet implemented
 
 Labeled arguments can be defined by wrapping parameters you wish to be labeled
 on call in curly braces.
@@ -203,7 +202,10 @@ let x = if 3 < val then: "hello" else: "bye"
 
 ## Loops
 
-Status: Not yet implemented
+> Status: Partially implemented.
+> - Tail call optimization fully implemented.
+> - While loops and break partially implemented. Do not yet support returning a value.
+> - For loops not yet implemented.
 
 While loops are the most basic looping construct
 
@@ -337,7 +339,7 @@ a union, they must have a case for each object in the union
 
 ## Traits
 
-Status: Not yet implemented
+> Status: Not yet implemented
 
 Traits define a set of behavior that can be implemented on any object type
 (nominal, structural, union, or intersection)
@@ -363,14 +365,23 @@ fn do_work(o: Object)
 
 ## Closures
 
-Status: Not yet implemented
+> Status: Not yet implemented
 
 ```rust
 let double = n => n * 2
 
 array.map n => n * 2
 ```
 
+Void also supports a concise syntax for passing closures to labeled arguments:
+
+```rust
+try do():
+  call_fn_that_has_exception_effect()
+catch:
+  print "Error!"
+```
+
 ## Dot Notation
 
 The dot is a simple form of syntactic sugar
@@ -386,8 +397,7 @@ squared(x)
 
 ## Generics
 
-Status: Basic implementation complete for objects, functions, impls, and type
-aliases. Inference is not yet supported.
+> Status: Basic implementation complete for objects, functions, impls, and type aliases. Inference is not yet supported.
 
 ```rust
 fn add<T>(a: T, b: T) -> T
@@ -403,7 +413,7 @@ fn add<T: Numeric>(a: T, b: T) -> T
 
 ## Effects
 
-Status: Not yet implemented
+> Status: Not yet implemented
 
 Effects (will be) a powerful construct of the voyd type system. Effects
 are useful for a large class of problems including type safe exceptions,
@@ -432,7 +442,7 @@ effect fn get() -> Int
 
 ## JSX
 
-Status: In Progress
+> Status: Implementation in progress
 
 Voyd has built in support for JSX. Useful for rendering websites or creating
 interactive web apps

src/__tests__/compiler.test.ts

@@ -57,6 +57,7 @@ describe("E2E Compiler Pipeline", () => {
       3,
       42,
       2, // IntersectionType tests
+      20, // While loop
     ]);
   });
 

src/__tests__/fixtures/e2e-file.ts

@@ -221,6 +221,16 @@ fn get_legs(a: Animal & { legs: i32 }) -> i32
 pub fn test18() -> i32
   let human = Mammal { age: 10, legs: 2 }
   get_legs(human)
+
+// Test while loops and breaking, should return 20
+pub fn test19() -> i32
+  var x = 0
+  var i = 0
+  while i < 10 do:
+    x = x + i * 2
+    i = i + 1
+    if i == 5 then: break
+  x
 `;
 
 export const tcoText = `

src/assembler.ts

@@ -50,6 +50,7 @@ export interface CompileExprOpts<T = Expr> {
   extensionHelpers: ReturnType<typeof initExtensionHelpers>;
   fieldLookupHelpers: ReturnType<typeof initFieldLookupHelpers>;
   isReturnExpr?: boolean;
+  loopBreakId?: string;
 }
 
 export const compileExpression = (opts: CompileExprOpts): number => {
@@ -195,6 +196,8 @@ const compileMatch = (opts: CompileExprOpts<Match>) => {
 const compileIdentifier = (opts: CompileExprOpts<Identifier>) => {
   const { expr, mod } = opts;
 
+  if (expr.is("break")) return mod.br(opts.loopBreakId!);
+
   const entity = expr.resolve();
   if (!entity) {
     throw new Error(`Unrecognized symbol ${expr.value}`);
@@ -220,7 +223,8 @@ const compileCall = (opts: CompileExprOpts<Call>): number => {
   if (expr.calls("export")) return compileExport(opts);
   if (expr.calls("mod")) return mod.nop();
   if (expr.calls("member-access")) return compileObjMemberAccess(opts);
-
+  if (expr.calls("while")) return compileWhile(opts);
+  if (expr.calls("break")) return mod.br(opts.loopBreakId!);
   if (expr.calls("binaryen")) {
     return compileBnrCall(opts);
   }
@@ -247,6 +251,35 @@ const compileCall = (opts: CompileExprOpts<Call>): number => {
   return mod.call(id, args, returnType);
 };
 
+const compileWhile = (opts: CompileExprOpts<Call>) => {
+  const { expr, mod } = opts;
+  const loopId = expr.syntaxId.toString();
+  const breakId = `__break_${loopId}`;
+  return mod.loop(
+    loopId,
+    mod.block(breakId, [
+      mod.br_if(
+        breakId,
+        mod.i32.ne(
+          compileExpression({
+            ...opts,
+            expr: expr.exprArgAt(0),
+            isReturnExpr: false,
+          }),
+          mod.i32.const(1)
+        )
+      ),
+      compileExpression({
+        ...opts,
+        expr: expr.labeledArgAt(1),
+        loopBreakId: breakId,
+        isReturnExpr: false,
+      }),
+      mod.br(loopId),
+    ])
+  );
+};
+
 const compileObjectInit = (opts: CompileExprOpts<Call>) => {
   const { expr, mod } = opts;
 

src/semantics/check-types.ts

@@ -52,8 +52,10 @@ const checkCallTypes = (call: Call): Call | ObjectLiteral => {
   if (call.calls("if")) return checkIf(call);
   if (call.calls("binaryen")) return checkBinaryenCall(call);
   if (call.calls("mod")) return call;
+  if (call.calls("break")) return call;
   if (call.calls(":")) return checkLabeledArg(call);
   if (call.calls("=")) return checkAssign(call);
+  if (call.calls("while")) return checkWhile(call);
   if (call.calls("member-access")) return call; // TODO
   if (call.fn?.isObjectType()) return checkObjectInit(call);
 
@@ -79,6 +81,19 @@ const checkCallTypes = (call: Call): Call | ObjectLiteral => {
   return call;
 };
 
+const checkWhile = (call: Call) => {
+  const cond = call.argAt(0);
+  const condType = getExprType(cond);
+  if (!cond || !condType || !typesAreCompatible(condType, bool)) {
+    throw new Error(
+      `While conditions must resolve to a boolean at ${cond?.location}`
+    );
+  }
+
+  checkTypes(call.argAt(1));
+  return call;
+};
+
 const checkObjectInit = (call: Call): Call => {
   const literal = call.argAt(0);
   if (!literal?.isObjectLiteral()) {
@@ -119,6 +134,8 @@ export const checkAssign = (call: Call) => {
 };
 
 const checkIdentifier = (id: Identifier) => {
+  if (id.is("return") || id.is("break")) return id;
+
   const entity = id.resolve();
   if (!entity) {
     throw new Error(`Unrecognized identifier, ${id} at ${id.location}`);

src/semantics/resolution/get-call-fn.ts

@@ -113,6 +113,9 @@ const isPrimitiveFnCall = (call: Call): boolean => {
     name === "return" ||
     name === "binaryen" ||
     name === ":" ||
-    name === "="
+    name === "=" ||
+    name === "while" ||
+    name === "for" ||
+    name === "break"
   );
 };

src/semantics/resolution/resolve-call-types.ts

@@ -12,6 +12,7 @@ export const resolveCallTypes = (call: Call): Call => {
   if (call.calls("export")) return resolveExport(call);
   if (call.calls("if")) return resolveIf(call);
   if (call.calls(":")) return checkLabeledArg(call);
+  if (call.calls("while")) return resolveWhile(call);
   call.args = call.args.map(resolveTypes);
 
   const memberAccessCall = getMemberAccessCall(call);
@@ -125,3 +126,9 @@ export const resolveIf = (call: Call) => {
   call.type = thenType;
   return call;
 };
+
+export const resolveWhile = (call: Call) => {
+  call.args = call.args.map(resolveTypes);
+  call.type = dVoid;
+  return call;
+};