src/main.rs

@@ -21,9 +21,9 @@
 //   - [x] with stack mechanics and refcounting
 //   - [ ] with tail-call optimization (nb: this may not be possible w/ a TW-VM)
 //   - [ ] with all the necessary forms for current Ludus
-//     * [x] guards in match clauses
+//     * [ ] guards in match clauses
 //     * [x] `as` patterns
-//     * [x] splat patterns in tuples, lists, dicts
+//     * [ ] splat patterns in tuples, lists, dicts
 //     * [ ] splats in list and dict literals
 //     * [ ] `loop` and `recur`
 //     * [ ] string patterns
@@ -55,14 +55,28 @@ use crate::base::*;
 
 pub fn main() {
     let src = "
-fn t () -> true
+fn fancy_add {
-fn f () -> false
+    () -> 0
-
+    (n as :number) -> n
-fn id {
+    (x as :number, y as :number) -> add (x, y)
-    (x) if f () -> x
-    (x) -> :whoops
 }
-id (:foo)
+
+fn fancy_sub {
+    () -> 0
+    (n as :number) -> n
+    (x as :number, y as :number) -> sub (x, y)
+}
+
+fn fib {
+   (1) -> 1
+   (2) -> 1
+   (n) -> fancy_add(
+       fib (fancy_sub (n, 1))
+       fib (fancy_sub (n, 2))
+   ) 
+}
+
+fib (30)
     ";
     let (tokens, lex_errs) = lexer().parse(src).into_output_errors();
     if lex_errs.len() > 0 {

src/parser.rs

@@ -211,12 +211,12 @@ pub enum Pattern<'src> {
     Keyword(&'src str),
     Word(&'src str),
     As(&'src str, &'src str),
-    Splattern(Box<Spanned<Self>>),
     Placeholder,
     Tuple(Vec<Spanned<Self>>),
     List(Vec<Spanned<Self>>),
-    Pair(&'src str, Box<Spanned<Self>>),
+    // is this the right representation for Dicts?
-    Dict(Vec<Spanned<Self>>),
+    // Could/should this also be a Vec?
+    Dict(Vec<Spanned<PairPattern<'src>>>),
 }
 
 impl<'src> fmt::Display for Pattern<'src> {
@@ -229,7 +229,6 @@ impl<'src> fmt::Display for Pattern<'src> {
             Pattern::Keyword(k) => write!(f, ":{}", k),
             Pattern::Word(w) => write!(f, "{}", w),
             Pattern::As(w, t) => write!(f, "{} as {}", w, t),
-            Pattern::Splattern(p) => write!(f, "...{}", (*p).0.to_string()),
             Pattern::Placeholder => write!(f, "_"),
             Pattern::Tuple(t) => write!(
                 f,
@@ -256,7 +255,6 @@ impl<'src> fmt::Display for Pattern<'src> {
                     .collect::<Vec<_>>()
                     .join(", ")
             ),
-            Pattern::Pair(key, value) => write!(f, ":{} {}", key, value.0),
         }
     }
 }
@@ -302,24 +300,8 @@ where
     }
     .map_with(|a, e| (a, e.span()));
 
-    let bare_splat = just(Token::Punctuation("...")).map_with(|_, e| {
-        (
-            Pattern::Splattern(Box::new((Pattern::Placeholder, e.span()))),
-            e.span(),
-        )
-    });
-
-    let splattable = word_pattern.clone().or(placeholder_pattern.clone());
-
-    let patt_splat = just(Token::Punctuation("..."))
-        .ignore_then(splattable)
-        .map_with(|x, e| (Pattern::Splattern(Box::new(x)), e.span()));
-
-    let splattern = patt_splat.or(bare_splat);
-
     let tuple_pattern = pattern
         .clone()
-        .or(splattern.clone())
         .separated_by(separators.clone())
         .allow_leading()
         .allow_trailing()
@@ -330,7 +312,6 @@ where
 
     let list_pattern = pattern
         .clone()
-        .or(splattern.clone())
         .separated_by(separators.clone())
         .allow_leading()
         .allow_trailing()
@@ -340,18 +321,20 @@ where
 
     let pair_pattern = select! {Token::Keyword(k) => k}
         .then(pattern.clone())
-        .map_with(|(key, patt), e| (Pattern::Pair(key, Box::new(patt)), e.span()));
+        .map_with(|(key, patt), e| (PairPattern { key, patt }, e.span()));
 
     let shorthand_pattern = select! {Token::Word(w) => w}.map_with(|w, e| {
         (
-            Pattern::Pair(w, Box::new((Pattern::Word(w), e.span()))),
+            PairPattern {
+                key: w,
+                patt: ((Pattern::Word(w), e.span())),
+            },
             e.span(),
         )
     });
 
     let dict_pattern = pair_pattern
         .or(shorthand_pattern)
-        .or(splattern.clone())
         .separated_by(separators.clone())
         .allow_leading()
         .allow_trailing()
@@ -521,18 +504,6 @@ where
         )
         .map_with(|clauses, e| (Ast::When(clauses), e.span()));
 
-    let guarded_clause = pattern
-        .clone()
-        .then_ignore(just(Token::Reserved("if")))
-        .then(simple.clone())
-        .then_ignore(just(Token::Punctuation("->")))
-        .then(expr.clone())
-        .map_with(|((patt, guard), body), _| MatchClause {
-            patt,
-            guard: Some(guard),
-            body,
-        });
-
     let match_clause = pattern
         .clone()
         .then_ignore(just(Token::Punctuation("->")))
@@ -549,7 +520,6 @@ where
         .then(
             match_clause
                 .clone()
-                .or(guarded_clause)
                 .separated_by(terminators.clone())
                 .allow_leading()
                 .allow_trailing()
@@ -586,19 +556,6 @@ where
         .then(block.clone())
         .map_with(|(count, body), e| (Ast::Repeat(Box::new(count), Box::new(body)), e.span()));
 
-    let fn_guarded = tuple_pattern
-        .clone()
-        .then_ignore(just(Token::Reserved("if")))
-        .then(simple.clone())
-        .then_ignore(just(Token::Punctuation("->")))
-        .then(nonbinding.clone())
-        .map_with(|((patt, guard), body), _| MatchClause {
-            patt,
-            body,
-            guard: Some(guard),
-        })
-        .labelled("function clause");
-
     let fn_clause = tuple_pattern
         .clone()
         .then_ignore(just(Token::Punctuation("->")))
@@ -669,7 +626,7 @@ where
 
     let fn_named = just(Token::Reserved("fn"))
         .ignore_then(word.clone())
-        .then(fn_clause.clone().or(fn_guarded.clone()))
+        .then(fn_clause.clone())
         .map_with(|(word, clause), e| {
             let name = if let Ast::Word(word) = word.0 {
                 word
@@ -684,7 +641,6 @@ where
         .then(
             fn_clause
                 .clone()
-                .or(fn_guarded.clone())
                 .separated_by(terminators.clone())
                 .allow_leading()
                 .allow_trailing()

src/vm.rs

@@ -79,112 +79,51 @@ pub fn match_pattern<'src, 'a>(
         }
         // todo: add splats to these match clauses
         (Pattern::Tuple(x), Value::Tuple(y)) => {
-            let has_splat = x.iter().any(|patt| {
+            if x.len() != y.len() {
-                if let (Pattern::Splattern(_), _) = patt {
-                    true
-                } else {
-                    false
-                }
-            });
-            if x.len() > y.len() || (!has_splat && x.len() != y.len()) {
                 return None;
             };
             let to = ctx.len();
             for i in 0..x.len() {
-                if let Pattern::Splattern(patt) = &x[i].0 {
+                if let None = match_pattern(&x[i].0, &y[i], ctx) {
-                    let mut list = Vector::new();
+                    while ctx.len() > to {
-                    for i in i..y.len() {
+                        ctx.pop();
-                        list.push_back(y[i].clone())
-                    }
-                    let list = Value::List(list);
-                    match_pattern(&(*patt).0, &list, ctx);
-                } else {
-                    if let None = match_pattern(&x[i].0, &y[i], ctx) {
-                        while ctx.len() > to {
-                            ctx.pop();
-                        }
-                        return None;
                     }
+                    return None;
                 }
             }
             Some(ctx)
         }
         (Pattern::List(x), Value::List(y)) => {
-            let has_splat = x.iter().any(|patt| {
+            if x.len() != y.len() {
-                if let (Pattern::Splattern(_), _) = patt {
-                    true
-                } else {
-                    false
-                }
-            });
-            if x.len() > y.len() || (!has_splat && x.len() != y.len()) {
                 return None;
             };
             let to = ctx.len();
             for i in 0..x.len() {
-                if let Pattern::Splattern(patt) = &x[i].0 {
+                if let None = match_pattern(&x[i].0, y.get(i).unwrap(), ctx) {
-                    let list = Value::List(y.skip(i));
+                    while ctx.len() > to {
-                    match_pattern(&(*patt).0, &list, ctx);
+                        ctx.pop();
-                } else {
-                    if let None = match_pattern(&x[i].0, &y.get(i).unwrap(), ctx) {
-                        while ctx.len() > to {
-                            ctx.pop();
-                        }
-                        return None;
                     }
+                    return None;
                 }
             }
             Some(ctx)
         }
-        // TODO: optimize this on several levels
-        // - [ ] opportunistic mutation
-        // - [ ] get rid of all the pointer indirection in word splats
         (Pattern::Dict(x), Value::Dict(y)) => {
-            let has_splat = x.iter().any(|patt| {
+            if x.len() != y.len() {
-                if let (Pattern::Splattern(_), _) = patt {
-                    true
-                } else {
-                    false
-                }
-            });
-            if x.len() > y.len() || (!has_splat && x.len() != y.len()) {
                 return None;
             };
             let to = ctx.len();
-            let mut matched = vec![];
+            for (PairPattern { key, patt }, _) in x {
-            for i in 0..x.len() {
+                if let Some(val) = y.get(key) {
-                let (pattern, _) = &x[i];
+                    if let None = match_pattern(&patt.0, val, ctx) {
-                match pattern {
+                        while ctx.len() > to {
-                    Pattern::Pair(key, patt) => {
+                            ctx.pop();
-                        if let Some(val) = y.get(key) {
-                            if let None = match_pattern(&patt.0, val, ctx) {
-                                while ctx.len() > to {
-                                    ctx.pop();
-                                    return None;
-                                }
-                            } else {
-                                matched.push(key);
-                            }
-                        } else {
                             return None;
-                        };
-                    }
-                    Pattern::Splattern(pattern) => match &(*pattern).0 {
-                        Pattern::Word(w) => {
-                            // TODO: find a way to take ownership
-                            // this will ALWAYS make structural changes, because of this clone
-                            // we want opportunistic mutation if possible
-                            let mut unmatched = y.clone();
-                            for key in matched.iter() {
-                                unmatched.remove(*key);
-                            }
-                            ctx.push((*w, Value::Dict(unmatched)));
                         }
-                        Pattern::Placeholder => (),
+                    }
-                        _ => unreachable!(),
+                } else {
-                    },
+                    return None;
-                    _ => unreachable!(),
+                };
-                }
             }
             Some(ctx)
         }
@@ -198,24 +137,8 @@ pub fn match_clauses<'src, 'a>(
     ctx: &'a mut Vec<(&'src str, Value<'src>)>,
 ) -> Result<Value<'src>, LudusError> {
     let to = ctx.len();
-    for MatchClause { patt, body, guard } in clauses.iter() {
+    for MatchClause { patt, body, .. } in clauses.iter() {
         if let Some(ctx) = match_pattern(&patt.0, value, ctx) {
-            let pass_guard = match guard {
-                None => true,
-                Some((ast, _)) => {
-                    let guard_res = eval(&ast, ctx);
-                    match &guard_res {
-                        Err(_) => return guard_res,
-                        Ok(val) => val.bool(),
-                    }
-                }
-            };
-            if !pass_guard {
-                while ctx.len() > to {
-                    ctx.pop();
-                }
-                continue;
-            }
             let res = eval(&body.0, ctx);
             while ctx.len() > to {
                 ctx.pop();
@@ -337,9 +260,7 @@ pub fn eval<'src, 'a>(
             let val = if let Some((_, value)) = ctx.iter().rev().find(|(name, _)| w == name) {
                 value.clone()
             } else {
-                return Err(LudusError {
+                unreachable!()
-                    msg: format!("unbound name {w}"),
-                });
             };
             Ok(val)
         }