work

src/parser/cursor/lit.rs

@@ -1,3 +1,5 @@
+use crate::parser::{DisplayCtx, FmtNode};
+
 use super::Token;
 
 #[derive(PartialEq)]
@@ -24,3 +26,9 @@ impl std::fmt::Display for Lit {
         }
     }
 }
+
+impl FmtNode for Lit {
+    fn fmt(&self, f: &mut std::fmt::Formatter, _: DisplayCtx) -> std::fmt::Result {
+        write!(f, "{self}")
+    }
+}

src/parser/cursor/mod.rs

@@ -54,6 +54,10 @@ impl<'a> Cursor<'a> {
         self.next().ok_or_else(CompilerMsg::unexpected_eof)
     }
 
+    pub fn expect_peek(&self) -> Result<&Token, CompilerMsg> {
+        self.peek().ok_or_else(CompilerMsg::unexpected_eof)
+    }
+
     pub fn expect(&mut self, token: Token) -> Result<Token, CompilerMsg> {
         let next = self.expect_next()?;
         if next == token {

src/parser/cursor/token.rs

@@ -28,6 +28,8 @@ def_tokens! {
         Hash: "#",
     }
     keyword {
+        Let: "let",
+        Do: "do",
         Fn: "fn",
         If: "if",
         Loop: "loop",

src/parser/node/parse.rs

@@ -15,7 +15,7 @@ pub trait Parsable: Sized + Node {
 pub struct ParseCtx<'a> {
     start: usize,
     cursor: Cursor<'a>,
-    nodes: Nodes,
+    pub nodes: Nodes,
 }
 
 impl<'a> ParseCtx<'a> {

src/parser/nodes/body.rs

@@ -1,13 +1,13 @@
 use super::*;
 
 pub struct Body {
-    pub exprs: Vec<Id<Expr>>,
+    pub items: Vec<Id<Item>>,
     pub final_semicolon: bool,
 }
 
 impl Parsable for Body {
     fn parse(ctx: &mut ParseCtx) -> Result<Self, CompilerMsg> {
-        let mut exprs = Vec::new();
+        let mut items = Vec::new();
         fn at_end(ctx: &mut ParseCtx) -> bool {
             ctx.peek().is_none_or(|t| *t == Token::CloseCurly)
         }
@@ -15,14 +15,19 @@ impl Parsable for Body {
             if at_end(ctx) {
                 break true;
             }
-            exprs.push(ctx.parse()?);
+            let item: Id<Item> = ctx.parse()?;
+            let needs_semicolon = item.needs_semicolon(&ctx.nodes);
+            items.push(item);
             if at_end(ctx) {
                 break false;
             }
+            if needs_semicolon {
                 ctx.expect(Token::Semicolon)?;
+            }
+            while ctx.next_if(Token::Semicolon) {}
         };
         Ok(Self {
-            exprs,
+            items,
             final_semicolon,
         })
     }
@@ -31,15 +36,27 @@ impl Parsable for Body {
 impl FmtNode for Body {
     fn fmt(&self, f: &mut std::fmt::Formatter, ctx: DisplayCtx) -> std::fmt::Result {
         // surely there's a better way to do this
-        if let Some((last, rest)) = self.exprs.split_last() {
+        if let Some((last, rest)) = self.items.split_last() {
             for &i in rest {
-                writeln!(f, "{}{};", " ".repeat(ctx.indent), i.dsp(ctx))?;
-            }
-            if self.final_semicolon {
-                writeln!(f, "{}{};", " ".repeat(ctx.indent), last.dsp(ctx))?;
+                writeln!(
+                    f,
+                    "{}{}{}",
+                    " ".repeat(ctx.indent),
+                    i.dsp(ctx),
+                    if i.needs_semicolon(ctx.nodes) {
+                        ";"
                     } else {
-                writeln!(f, "{}{}", " ".repeat(ctx.indent), last.dsp(ctx))?;
+                        ""
                     }
+                )?;
+            }
+            writeln!(
+                f,
+                "{}{}{}",
+                " ".repeat(ctx.indent),
+                last.dsp(ctx),
+                if self.final_semicolon { ";" } else { "" }
+            )?;
         }
         Ok(())
     }

src/parser/nodes/expr.rs

@@ -16,11 +16,6 @@ pub enum Expr {
         target: Id<Expr>,
         val: Id<Expr>,
     },
-    Define {
-        target: Id<Expr>,
-        ty: Option<Id<Type>>,
-        val: Id<Expr>,
-    },
     If {
         cond: Id<Expr>,
         body: Id<Expr>,
@@ -45,16 +40,6 @@ impl Parsable for Expr {
                     let val = ctx.parse_with(Self::unit)?;
                     Expr::Assign { target, val }
                 }
-                Token::Colon => {
-                    let target = ctx.push_adv(res);
-                    let mut ty = None;
-                    if !ctx.next_if(Token::Equal) {
-                        ty = Some(ctx.parse()?);
-                        ctx.expect(Token::Equal)?;
-                    }
-                    let val = ctx.parse_with(Self::unit)?;
-                    Expr::Define { target, ty, val }
-                }
                 Token::OpenParen => {
                     let target = ctx.push_adv(res);
                     let args = ctx.list(Token::Comma, Token::CloseParen)?;
@@ -76,12 +61,12 @@ impl Expr {
             Token::Fn => Self::Fn(ctx.parse()?),
             Token::If => {
                 let cond = ctx.parse()?;
-                let body = cond_body(cond, ctx)?;
+                let body = cond_body(ctx)?;
                 Self::If { cond, body }
             }
             Token::While => {
                 let cond = ctx.parse()?;
-                let body = cond_body(cond, ctx)?;
+                let body = cond_body(ctx)?;
                 Self::While { cond, body }
             }
             Token::Loop => {
@@ -110,6 +95,10 @@ impl Expr {
         matches!(self, Expr::Group(_))
     }
 
+    pub fn is_block(&self) -> bool {
+        matches!(self, Expr::Block(_))
+    }
+
     pub fn block(ctx: &mut ParseCtx) -> Result<Expr, CompilerMsg> {
         ctx.expect(Token::OpenCurly)?;
         let id = ctx.parse()?;
@@ -118,16 +107,32 @@ impl Expr {
     }
 }
 
-fn cond_body(cond: Id<Expr>, ctx: &mut ParseCtx) -> Result<Id<Expr>, CompilerMsg> {
-    if ctx[cond].is_group() {
+fn cond_body(ctx: &mut ParseCtx) -> Result<Id<Expr>, CompilerMsg> {
+    if ctx.next_if(Token::Do) {
         ctx.parse()
     } else {
         ctx.parse_with(Expr::block)
     }
 }
 
+impl Id<Expr> {
+    pub fn ends_with_block(&self, nodes: &Nodes) -> bool {
+        match nodes[self] {
+            Expr::Block(..) => true,
+            Expr::Loop { body }
+            | Expr::While { body, .. }
+            | Expr::If { body, .. }
+            | Expr::Negate(body)
+            | Expr::Assign { val: body, .. } => body.ends_with_block(nodes),
+            Expr::Fn(f) => f.ends_with_block(nodes),
+            _ => false,
+        }
+    }
+}
+
 impl FmtNode for Expr {
     fn fmt(&self, f: &mut std::fmt::Formatter, mut ctx: DisplayCtx) -> std::fmt::Result {
+        let do_ = |id: Id<Expr>| if ctx.nodes[id].is_block() { "" } else { "do " };
         match *self {
             Self::Ident(id) => id.fmt(f, ctx),
             Self::Group(id) => write!(f, "({})", id.dsp(ctx)),
@@ -142,27 +147,18 @@ impl FmtNode for Expr {
             Self::Assign { target, val } => {
                 write!(f, "{} = {}", target.dsp(ctx), val.dsp(ctx))
             }
-            Self::Define { target, ty, val } => {
-                target.fmt(f, ctx)?;
-                if let Some(ty) = ty {
-                    write!(f, ": {} ", ty.dsp(ctx))?;
-                } else {
-                    write!(f, " :")?;
-                }
-                write!(f, "= {}", val.dsp(ctx))
-            }
             Self::If { cond, body } => {
-                write!(f, "if {} {}", cond.dsp(ctx), body.dsp(ctx))
+                write!(f, "if {} {}{}", cond.dsp(ctx), do_(body), body.dsp(ctx))
             }
             Self::While { cond, body } => {
-                write!(f, "while {} {}", cond.dsp(ctx), body.dsp(ctx))
+                write!(f, "while {} {}{}", cond.dsp(ctx), do_(body), body.dsp(ctx))
             }
             Self::Loop { body } => {
                 write!(f, "loop {}", body.dsp(ctx))
             }
             Self::Block(body) => {
                 write!(f, "{{")?;
-                if !ctx.nodes[body].exprs.is_empty() {
+                if !ctx.nodes[body].items.is_empty() {
                     writeln!(f)?;
                     ctx.indent += 3;
                     body.fmt(f, ctx)?;
@@ -173,9 +169,3 @@ impl FmtNode for Expr {
         }
     }
 }
-
-impl FmtNode for Lit {
-    fn fmt(&self, f: &mut std::fmt::Formatter, _: DisplayCtx) -> std::fmt::Result {
-        write!(f, "{self}")
-    }
-}

src/parser/nodes/func.rs

@@ -40,3 +40,9 @@ impl FmtNode for Func {
         Ok(())
     }
 }
+
+impl Id<Func> {
+    pub fn ends_with_block(&self, nodes: &Nodes) -> bool {
+        nodes[self].body.ends_with_block(nodes)
+    }
+}

src/parser/nodes/item.rs

@@ -0,0 +1,58 @@
+use super::*;
+
+pub enum Item {
+    Let {
+        name: Id<Ident>,
+        ty: Option<Id<Type>>,
+        val: Id<Expr>,
+    },
+    Struct(Id<Struct>),
+    Expr(Id<Expr>),
+}
+
+impl Parsable for Item {
+    fn parse(ctx: &mut ParseCtx) -> Result<Self, CompilerMsg> {
+        Ok(match ctx.expect_peek()? {
+            Token::Let => {
+                ctx.next();
+                let name = ctx.parse()?;
+                let mut ty = None;
+                if ctx.next_if(Token::Colon) {
+                    ty = Some(ctx.parse()?);
+                }
+                ctx.expect(Token::Equal)?;
+                let val = ctx.parse()?;
+                Self::Let { name, ty, val }
+            }
+            _ => Self::Expr(ctx.parse()?),
+        })
+    }
+}
+
+impl FmtNode for Item {
+    fn fmt(&self, f: &mut std::fmt::Formatter, ctx: DisplayCtx) -> std::fmt::Result {
+        match self {
+            Item::Let { name, ty, val } => {
+                write!(f, "let {}", name.dsp(ctx))?;
+                if let Some(ty) = ty {
+                    write!(f, ": {}", ty.dsp(ctx))?;
+                }
+                write!(f, " = {}", val.dsp(ctx))?;
+            }
+            Item::Expr(id) => id.fmt(f, ctx)?,
+        }
+        Ok(())
+    }
+}
+
+impl Id<Item> {
+    pub fn ends_with_block(&self, nodes: &Nodes) -> bool {
+        match nodes[self] {
+            Item::Let { name, ty, val } => val.ends_with_block(nodes),
+            Item::Expr(id) => id.ends_with_block(nodes),
+        }
+    }
+    pub fn needs_semicolon(&self, nodes: &Nodes) -> bool {
+        !self.ends_with_block(nodes)
+    }
+}

src/parser/nodes/mod.rs

@@ -2,13 +2,17 @@ mod body;
 mod expr;
 mod func;
 mod ident;
+mod item;
 mod param;
+mod struct_;
 mod ty;
 pub use body::*;
 pub use expr::*;
 pub use func::*;
 pub use ident::*;
+pub use item::*;
 pub use param::*;
+pub use struct_::*;
 pub use ty::*;
 
 use super::{DisplayCtx, FmtNode, Id, Lit, Node, NodeVec, Parsable, ParseCtx, Token};
@@ -22,6 +26,8 @@ def_nodes! {
     types: Type,
     funcs: Func,
     params: Param,
+    items: Item,
+    structs: Struct,
 }
 
 macro_rules! def_nodes {

src/parser/nodes/struct_.rs

@@ -0,0 +1,14 @@
+use super::*;
+
+pub struct Struct {
+    name: String,
+    fields: Vec<Field>,
+}
+
+impl Parsable for Struct {
+    fn parse(ctx: &mut ParseCtx) -> Result<Self, CompilerMsg> {
+    }
+}
+
+pub struct Field {
+}

test/main.lang

@@ -1,7 +1,11 @@
-x :i32 = 3;
+let x: i32 = 3;
 while true {
     print("hello");
     print(x);
 };
 
-y := fn(x: i32) -> i32 {x};
+if x {
+    print("hello");
+}
+
+let y = fn(x: i32) -> i32 {x};