Improved grammar

src/parser/grammar.pest

@@ -13,40 +13,65 @@ string_lit =  { "\"" ~ inner_str ~ "\"" }
 inner_str  = @{ (!"\"" ~ ANY)* }
 
 // top level
-import_decl  =  { "import" ~ string_lit }
+import_decl = { "import" ~ string_lit ~ ";" }
-struct_decl  =  { "struct" ~ identifier ~ "{" ~ struct_field* ~ "}" }
+
-class_decl   =  { "class" ~ identifier ~ "{" ~ class_member* ~ "}" }
+struct_decl = {
+    "struct" ~ identifier ~ "{" ~ struct_field* ~ "}"
+}
+
+class_decl = {
+    "class" ~ identifier ~ "{" ~ class_member* ~ "}"
+}
+
 class_member = _{ struct_field | function_decl }
 
-function_decl = { "fn" ~ identifier ~ "(" ~ param_list? ~ ")" ~ ("->" ~ type_expr)? ~ block }
+function_decl = {
+    "fn" ~ identifier ~ "(" ~ param_list? ~ ")" ~ ("->" ~ type_expr)? ~ block
+}
 
-struct_field = { identifier ~ ":" ~ type_expr }
+// struct fields (NO commas, Go-style)
-param_list   = { param ~ ("," ~ param)* }
+struct_field = { identifier ~ ":" ~ type_expr ~ ";" }
-param        = { identifier ~ ":" ~ type_expr }
+
+// params (allow trailing comma)
+param_list = { param ~ ("," ~ param)* ~ ","? }
+param      = { identifier ~ ":" ~ type_expr }
 
 // statements
-block     =  { "{" ~ statement* ~ "}" }
+block = { "{" ~ statement* ~ "}" }
+
 statement = _{
     let_stmt
   | return_stmt
   | if_stmt
   | for_stmt
   | assign_stmt
-  | expression
+  | expression_stmt
 }
 
-assign_stmt = { identifier ~ "=" ~ expression }
+expression_stmt = { expression ~ ";" }
-let_stmt    = { "let" ~ identifier ~ (":" ~ type_expr)? ~ "=" ~ expression }
+
-return_stmt = { "return" ~ expression? }
+assign_stmt = { identifier ~ "=" ~ expression ~ ";" }
-if_stmt     = { "if" ~ expression ~ block ~ ("else" ~ block)? }
+
-for_stmt    = { "for" ~ identifier ~ "in" ~ expression ~ block }
+let_stmt = {
+    "let" ~ identifier ~ (":" ~ type_expr)? ~ "=" ~ expression ~ ";"
+}
+
+return_stmt = { "return" ~ expression? ~ ";" }
+
+if_stmt = {
+    "if" ~ expression ~ block ~ ("else" ~ block)?
+}
+
+for_stmt = {
+    "for" ~ identifier ~ "in" ~ expression ~ block
+}
 
 // types
 type_expr  =  { base_type ~ "?"? }
 base_type  = _{ array_type | identifier }
 array_type =  { "[" ~ type_expr ~ "]" }
 
-// expressions (still simple, no precedence yet)
+// expressions (still no precedence yet)
 expression = { term ~ (bin_op ~ term)* }
 
 bin_op = _{
@@ -78,6 +103,7 @@ and = { "&&" }
 or  = { "||" }
 
 // literals
+
 struct_literal = {
     identifier ~ "{" ~ struct_init_list? ~ "}"
 }
@@ -94,7 +120,7 @@ array_literal = {
     "[" ~ (expression ~ ("," ~ expression)*)? ~ ","? ~ "]"
 }
 
-// expressions continuation
+// chaining
 term = { primary ~ (field_access | call_suffix)* }
 
 field_access = { "." ~ identifier }
@@ -103,6 +129,7 @@ call_suffix = {
     "(" ~ (expression ~ ("," ~ expression)*)? ~ ","? ~ ")"
 }
 
+// primary
 primary = _{
     struct_literal
   | array_literal

test/main.ms

@@ -1,120 +1,120 @@
-import "fmt"
+import "fmt";
-import "strings"
+import "strings";
 
 // structs are plain data
 struct Point {
-    x: float
+    x: float;
-    y: float
+    y: float;
 }
 
 // classes have fields and methods
 class Animal {
-    name: string
+    name: string;
-    age: int
+    age: int;
 
     fn speak() -> string {
-        return "..."
+        return "...";
     }
 
     fn describe() -> string {
-        return "I am " + self.name
+        return "I am " + self.name;
     }
 }
 
 class Dog {
-    name: string
+    name: string;
-    age: int
+    age: int;
 
     fn speak() -> string {
-        return "Woof!"
+        return "Woof!";
     }
 
     fn fetch(item: string) -> string {
-        return self.name + " fetched the " + item
+        return self.name + " fetched the " + item;
     }
 }
 
 // basic function
 fn add(a: int, b: int) -> int {
-    return a + b
+    return a + b;
 }
 
 // optional return type
 fn find(name: string) -> string? {
     if name == "mist" {
-        return name
+        return name;
     }
-    return null
+    return null;
 }
 
 // array types
 fn sum(numbers: [int]) -> int {
-    let total: int = 0
+    let total: int = 0;
     for n in numbers {
-        total = total + n
+        total = total + n;
     }
-    return total
+    return total;
 }
 
 // multiple params, no return
 fn greet(first: string, last: string) {
-    let full: string = first + " " + last
+    let full: string = first + " " + last;
-    print(full)
+    print(full);
 }
 
 // structs initialized with fields
 fn make_point(x: float, y: float) -> Point {
     return Point {
         x: x,
-        y: y
+        y: y,
-    }
+    };
 }
 
 // if / else
 fn classify(n: int) -> string {
     if n < 0 {
-        return "negative"
+        return "negative";
     } else {
-        return "positive"
+        return "positive";
     }
 }
 
 // entry point
 fn main() {
     // variables
-    let x: int = 10
+    let x: int = 10;
-    let y: int = 20
+    let y: int = 20;
-    let result: int = add(x, y)
+    let result: int = add(x, y);
 
     // inferred (no type annotation)
-    let message = "Hello from Mist!"
+    let message = "Hello from Mist!";
-    print(message)
+    print(message);
 
     // struct usage
-    let p: Point = make_point(1.5, 2.5)
+    let p: Point = make_point(1.5, 2.5);
-    print(p.x)
+    print(p.x);
 
     // class usage
     let dog: Dog = Dog {
         name: "Rex",
-        age: 3
+        age: 3,
-    }
+    };
-    print(dog.speak())
+    print(dog.speak());
-    print(dog.fetch("ball"))
+    print(dog.fetch("ball"));
 
     // arrays
-    let nums: [int] = [1, 2, 3, 4, 5]
+    let nums: [int] = [1, 2, 3, 4, 5];
-    let total: int = sum(nums)
+    let total: int = sum(nums);
-    print(total)
+    print(total);
 
     // for loop
     for n in nums {
-        print(n)
+        print(n);
     }
 
     // optional
-    let found: string? = find("mist")
+    let found: string? = find("mist");
     if found {
-        print(found)
+        print(found);
     }
 }