one or more holes in piping, (almost) mutable variable

crates/codegen/src/ts.rs

@@ -31,9 +31,10 @@ impl Codegen {
         macro_rules! semicolon { () => { if should_gen_semicolon { ";" } else { "" } }; }
 
         match ir {
-            IRKind::Define { name, type_hint, value } => {
+            IRKind::Define { name, type_hint, value, mutable } => {
                 format!(
-                    "const {}: {} = {}{}\n",
+                    "{} {}: {} = {}{}\n",
+                    if *mutable { "let" } else { "const" },
                     name, 
                     type_hint,
                     self.gen_ir(value, false),

crates/hir/src/lib.rs

@@ -13,7 +13,7 @@ pub enum Value { Int(i64), Boolean(bool), String(String), Ident(String) }
 
 #[derive(Debug, Clone)]
 pub enum IRKind {
-    Define { name: String, type_hint: String, value: Box<Self> },
+    Define { name: String, type_hint: String, value: Box<Self>, mutable: bool },
     Fun { name: String, return_type_hint: String, args: Vec<(String, String)>, body: Box<Self> },
     Call { name: String, args: Vec<Self> },
     Intrinsic { name: String, args: Vec<Self> },
@@ -115,14 +115,16 @@ pub fn expr_to_ir(expr: &Expr) -> (Option<IRKind>, Option<LoweringError>) {
                         _ => return (None, Some(LoweringError { span: name.1.clone(), message: "Expected identifier".to_string(), note: None }))
                     };
 
-                    // Get the index where the `Hole` is at
-                    let index = args.0.iter().position(|arg| match arg.0 {
-                        Expr::Hole(..) => true,
-                        _ => false
-                    });
+                    // Get all the `Hole` indexes
+                    let mut indexes = Vec::new();
+                    for (i, arg) in args.0.iter().enumerate() {
+                        if let Expr::Hole(..) = &arg.0 {
+                            indexes.push(i);
+                        }
+                    }
 
                     // If there is no `Hole` in the args then return early
-                    if let None = index {
+                    if indexes.is_empty() {
                         return (None, Some(LoweringError {
                             span: rhs.1.clone(),
                             message: "Expected hole in piping".to_string(),
@@ -132,7 +134,9 @@ pub fn expr_to_ir(expr: &Expr) -> (Option<IRKind>, Option<LoweringError>) {
 
                     // Remove the `Hole` from the args
                     let mut new_args = args.0.clone();
-                    new_args.remove(index.unwrap());
+                    for index in indexes.iter().rev() {
+                        new_args.remove(*index);
+                    }
 
                     // Make a new call expression with the new args
                     let new_call = match call {
@@ -182,12 +186,18 @@ pub fn expr_to_ir(expr: &Expr) -> (Option<IRKind>, Option<LoweringError>) {
             };
         },
 
-        Expr::Let { name, type_hint, value } => {
+        Expr::Let { name, type_hint, value, mutable } => {
             let value = expr_to_ir(&value.0);
             if_err_return!(value.1);
 
             let value = value.0.unwrap();
-            let ir_kind = IRKind::Define { name: name.clone(), type_hint: gen_type_hint(type_hint), value: Box::new(value) };
+            let ir_kind = IRKind::Define {
+                name: name.clone(),
+                type_hint: gen_type_hint(type_hint),
+                value: Box::new(value),
+                mutable: *mutable
+            };
+
             return (Some(ir_kind), None);
         },
 

crates/lexer/src/lib.rs

@@ -3,7 +3,7 @@ use chumsky::prelude::*;
 #[derive(Clone, Debug, PartialEq, Eq, Hash)]
 pub enum Token {
     // Keywords
-    KwLet, KwFun,
+    KwLet, KwMut, KwFun,
     KwDo, KwEnd,
     KwIf, KwThen, KwElse,
     KwReturn,
@@ -30,6 +30,7 @@ impl std::fmt::Display for Token {
     fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
         match self {
             Token::KwLet => write!(f, "let"),
+            Token::KwMut => write!(f, "mut"),
             Token::KwFun => write!(f, "fun"),
             Token::KwDo => write!(f, "do"),
             Token::KwEnd => write!(f, "end"),

crates/parser/src/lib.rs

@@ -18,6 +18,7 @@ pub enum Expr {
         name: String,
         type_hint: String,
         value: Box<Spanned<Self>>,
+        mutable: bool,
     },
     Fun {
         name: String,
@@ -193,17 +194,19 @@ fn expr_parser() -> impl Parser<Token, Vec<Spanned<Expr>>, Error = Simple<Token>
             });
 
         let let_ = just(Token::KwLet)
-            .ignore_then(identifier)
+            .ignore_then(just(Token::KwMut)).or_not()
+            .then(identifier)
             .then_ignore(just(Token::Colon))
             .then(identifier)
             .then_ignore(just(Token::Assign))
             .then(expr.clone())
-            .map(|((name, type_hint), value)| {
+            .map(|(((mutable, name), type_hint), value)| {
                 (
                     Expr::Let {
                         name: name.0.clone(),
                         type_hint: type_hint.0,
                         value: Box::new(value.clone()),
+                        mutable: mutable.is_some(),
                     },
                     name.1.start..value.1.end,
                 )

example/pipe2.hz

@@ -12,4 +12,8 @@ fun main: void = do
     |> qux(_)
     |> quux(1, _)
     |> @write(_);
+
+    210
+    |> bar(_, _)
+    |> @write(_);
 end;