diff --git a/crates/haku-wasm/src/lib.rs b/crates/haku-wasm/src/lib.rs
index 8459dc6..0e21b02 100644
--- a/crates/haku-wasm/src/lib.rs
+++ b/crates/haku-wasm/src/lib.rs
@@ -6,7 +6,7 @@ use core::{alloc::Layout, mem, ptr, slice};
 
 use alloc::{boxed::Box, string::String, vec::Vec};
 use haku::{
-    ast::{self, Ast},
+    ast::Ast,
     bytecode::{Chunk, Defs, DefsImage, DefsLimits},
     compiler::{compile_expr, ClosureSpec, CompileError, Compiler, Source},
     diagnostic::Diagnostic,
@@ -48,6 +48,12 @@ struct Limits {
     max_parser_events: usize,
     ast_capacity: usize,
     chunk_capacity: usize,
+    stack_capacity: usize,
+    call_stack_capacity: usize,
+    ref_capacity: usize,
+    fuel: usize,
+    memory: usize,
+    render_max_depth: usize,
 }
 
 impl Default for Limits {
@@ -61,6 +67,12 @@ impl Default for Limits {
             max_parser_events: 1024,
             ast_capacity: 1024,
             chunk_capacity: 65536,
+            stack_capacity: 1024,
+            call_stack_capacity: 256,
+            ref_capacity: 2048,
+            fuel: 65536,
+            memory: 1024 * 1024,
+            render_max_depth: 256,
         }
     }
 }
@@ -100,6 +112,12 @@ limit_setter!(max_tokens);
 limit_setter!(max_parser_events);
 limit_setter!(ast_capacity);
 limit_setter!(chunk_capacity);
+limit_setter!(stack_capacity);
+limit_setter!(call_stack_capacity);
+limit_setter!(ref_capacity);
+limit_setter!(fuel);
+limit_setter!(memory);
+limit_setter!(render_max_depth);
 
 #[derive(Debug, Clone)]
 struct Instance {
@@ -478,24 +496,22 @@ unsafe extern "C" fn haku_num_diagnostics(instance: *const Instance) -> u32 {
 
 #[unsafe(no_mangle)]
 unsafe extern "C" fn haku_diagnostic_start(instance: *const Instance, index: u32) -> u32 {
-    (&(*instance).diagnostics2)[index as usize].span().start
+    (*instance).diagnostics2[index as usize].span().start
 }
 
 #[unsafe(no_mangle)]
 unsafe extern "C" fn haku_diagnostic_end(instance: *const Instance, index: u32) -> u32 {
-    (&(*instance).diagnostics2)[index as usize].span().end
+    (*instance).diagnostics2[index as usize].span().end
 }
 
 #[unsafe(no_mangle)]
 unsafe extern "C" fn haku_diagnostic_message(instance: *const Instance, index: u32) -> *const u8 {
-    (&(*instance).diagnostics2)[index as usize]
-        .message()
-        .as_ptr()
+    (*instance).diagnostics2[index as usize].message().as_ptr()
 }
 
 #[unsafe(no_mangle)]
 unsafe extern "C" fn haku_diagnostic_message_len(instance: *const Instance, index: u32) -> u32 {
-    (&(*instance).diagnostics2)[index as usize].message().len() as u32
+    (*instance).diagnostics2[index as usize].message().len() as u32
 }
 
 #[unsafe(no_mangle)]
diff --git a/crates/haku/src/lexer.rs b/crates/haku/src/lexer.rs
index f3e4ce2..64683a9 100644
--- a/crates/haku/src/lexer.rs
+++ b/crates/haku/src/lexer.rs
@@ -3,7 +3,7 @@ use alloc::vec::Vec;
 use crate::{
     diagnostic::Diagnostic,
     source::{SourceCode, Span},
-    token::{Lexis, Spaces, TokenAllocError, TokenKind},
+    token::{Lexis, TokenAllocError, TokenKind},
 };
 
 pub struct Lexer<'a> {
@@ -57,7 +57,7 @@ fn one_or_two(l: &mut Lexer<'_>, kind1: TokenKind, c2: char, kind2: TokenKind) -
 }
 
 fn is_ident_char(c: char) -> bool {
-    matches!(c, 'a'..='z' | 'A'..='Z' | '0'..='9' | '_' | '\'' | '?')
+    matches!(c, 'a'..='z' | 'A'..='Z' | '0'..='9' | '_')
 }
 
 fn ident(l: &mut Lexer<'_>) -> TokenKind {
@@ -132,8 +132,7 @@ fn color(l: &mut Lexer<'_>) -> TokenKind {
     TokenKind::Color
 }
 
-fn whitespace_and_comments(l: &mut Lexer<'_>) -> bool {
-    let mut matched = false;
+fn whitespace_and_comments(l: &mut Lexer<'_>) {
     loop {
         match l.current() {
             '-' => {
@@ -143,7 +142,6 @@ fn whitespace_and_comments(l: &mut Lexer<'_>) -> bool {
                     while l.current() != '\n' && l.current() != '\0' {
                         l.advance();
                     }
-                    matched = true;
                 } else {
                     // An unfortunate little bit of backtracking here;
                     // This seems like the simplest possible solution though.
@@ -155,18 +153,14 @@ fn whitespace_and_comments(l: &mut Lexer<'_>) -> bool {
                 }
             }
 
-            ' ' | '\r' | '\t' => {
-                l.advance();
-                matched = true
-            }
+            ' ' | '\r' | '\t' => l.advance(),
 
             _ => break,
         }
     }
-    matched
 }
 
-fn newline(l: &mut Lexer<'_>, has_left_space: bool) -> (TokenKind, Span, bool) {
+fn newline(l: &mut Lexer<'_>) -> (TokenKind, Span) {
     let start = l.position;
     l.advance(); // skip the initial newline
     let end = l.position;
@@ -183,11 +177,11 @@ fn newline(l: &mut Lexer<'_>, has_left_space: bool) -> (TokenKind, Span, bool) {
         }
     }
 
-    (TokenKind::Newline, Span::new(start, end), has_left_space)
+    (TokenKind::Newline, Span::new(start, end))
 }
 
-fn token(l: &mut Lexer<'_>) -> (TokenKind, Span, bool) {
-    let has_left_space = whitespace_and_comments(l);
+fn token(l: &mut Lexer<'_>) -> (TokenKind, Span) {
+    whitespace_and_comments(l);
 
     let start = l.position;
     let kind = match l.current() {
@@ -209,7 +203,7 @@ fn token(l: &mut Lexer<'_>) -> (TokenKind, Span, bool) {
         '<' => one_or_two(l, TokenKind::Less, '=', TokenKind::LessEqual),
         '>' => one_or_two(l, TokenKind::Greater, '=', TokenKind::GreaterEqual),
 
-        '\n' => return newline(l, has_left_space),
+        '\n' => return newline(l),
         '(' => one(l, TokenKind::LParen),
         ')' => one(l, TokenKind::RParen),
         '[' => one(l, TokenKind::LBrack),
@@ -228,22 +222,13 @@ fn token(l: &mut Lexer<'_>) -> (TokenKind, Span, bool) {
         }
     };
     let end = l.position;
-    (kind, Span::new(start, end), has_left_space)
+    (kind, Span::new(start, end))
 }
 
 pub fn lex(l: &mut Lexer<'_>) -> Result<(), TokenAllocError> {
     loop {
-        let (kind, span, has_left_space) = token(l);
-
-        if !l.lexis.is_empty() {
-            let prev = l.lexis.len() - 1;
-            let spaces = l.lexis.spaces(prev);
-            l.lexis
-                .set_spaces(prev, Spaces::new(spaces.left(), has_left_space));
-        }
-        let spaces = Spaces::new(has_left_space, false);
-        l.lexis.push(kind, spaces, span)?;
-
+        let (kind, span) = token(l);
+        l.lexis.push(kind, span)?;
         if kind == TokenKind::Eof {
             break;
         }
diff --git a/crates/haku/src/parser.rs b/crates/haku/src/parser.rs
index a8e0cee..a64aad8 100644
--- a/crates/haku/src/parser.rs
+++ b/crates/haku/src/parser.rs
@@ -7,7 +7,7 @@ use crate::{
     ast::{Ast, NodeAllocError, NodeId, NodeKind},
     diagnostic::Diagnostic,
     source::Span,
-    token::{Lexis, Spaces, TokenKind, TokenKindSet},
+    token::{Lexis, TokenKind, TokenKindSet},
 };
 
 #[derive(Debug, Clone, Copy)]
@@ -132,11 +132,6 @@ impl<'a> Parser<'a> {
         self.tokens.kind(self.position)
     }
 
-    #[track_caller]
-    fn peek_with_spaces(&self) -> (TokenKind, Spaces) {
-        (self.peek(), self.tokens.spaces(self.position))
-    }
-
     fn span(&self) -> Span {
         self.tokens.span(self.position)
     }
@@ -303,61 +298,33 @@ impl fmt::Display for IntoAstError {
 
 impl Error for IntoAstError {}
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
 enum Tighter {
     Left,
     Right,
 }
 
-fn tighter(left: (TokenKind, Spaces), right: (TokenKind, Spaces)) -> Tighter {
-    #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
-    enum Spacing {
-        Loose,
-        Call,
-        Tight,
-    }
-
-    fn tightness((kind, spaces): (TokenKind, Spaces)) -> Option<(Spacing, usize)> {
-        let spacing = match kind {
-            // There are a few types of operators which are independent of tightness.
-
-            // For : and =, it does not matter if they're spelled one way or the other, because
-            // there is only one way to use them (at the beginning of the expression).
-            TokenKind::Colon | TokenKind::Equal => Spacing::Loose,
-
-            // For calls, there is a special intermediate level, such that they can sit between
-            // loose operators and tight operators.
-            _ if PREFIX_TOKENS.contains(kind) => Spacing::Call,
-
-            // For everything else, the usual rules apply.
-            _ => match spaces.pair() {
-                (false, false) => Spacing::Tight,
-                (true, true) => Spacing::Loose,
-                _ => return None, // not a valid infix operator
-            },
-        };
-        let index = match kind {
-            TokenKind::Equal | TokenKind::Colon => 0,
-            // 1: reserved for `and` and `or`
+fn tighter(left: TokenKind, right: TokenKind) -> Tighter {
+    fn tightness(kind: TokenKind) -> Option<usize> {
+        match kind {
+            TokenKind::Equal | TokenKind::Colon => Some(0),
             TokenKind::EqualEqual
             | TokenKind::NotEqual
             | TokenKind::Less
             | TokenKind::LessEqual
             | TokenKind::Greater
-            | TokenKind::GreaterEqual => 2,
-            TokenKind::Plus | TokenKind::Minus | TokenKind::Star | TokenKind::Slash => 3,
-            // 4: reserve for `.`
-            _ if PREFIX_TOKENS.contains(kind) => 5,
-            _ => return None, // not an infix operator
-        };
-        Some((spacing, index))
+            | TokenKind::GreaterEqual => Some(1),
+            TokenKind::Plus | TokenKind::Minus => Some(2),
+            TokenKind::Star | TokenKind::Slash => Some(3),
+            _ if PREFIX_TOKENS.contains(kind) => Some(4),
+            _ => None,
+        }
     }
 
     let Some(right_tightness) = tightness(right) else {
         return Tighter::Left;
     };
     let Some(left_tightness) = tightness(left) else {
-        assert!(left.0 == TokenKind::Eof);
+        assert!(left == TokenKind::Eof);
         return Tighter::Right;
     };
 
@@ -368,13 +335,12 @@ fn tighter(left: (TokenKind, Spaces), right: (TokenKind, Spaces)) -> Tighter {
     }
 }
 
-fn precedence_parse(p: &mut Parser, left: (TokenKind, Spaces)) {
+fn precedence_parse(p: &mut Parser, left: TokenKind) {
     let mut lhs = prefix(p);
 
     loop {
-        let right = p.peek_with_spaces();
-        let tighter = tighter(left, right);
-        match tighter {
+        let right = p.peek();
+        match tighter(left, right) {
             Tighter::Left => break,
             Tighter::Right => {
                 let o = p.open_before(lhs);
@@ -570,12 +536,55 @@ fn if_expr(p: &mut Parser) -> Closed {
     p.close(o, NodeKind::If)
 }
 
-// NOTE: This must be synchronised with the match expression in prefix().
+fn let_expr(p: &mut Parser) -> Closed {
+    let o = p.open();
+
+    p.advance(); // let
+
+    if p.peek() == TokenKind::Ident {
+        let ident = p.open();
+        p.advance();
+        p.close(ident, NodeKind::Ident);
+    } else {
+        let span = p.span();
+        p.emit(Diagnostic::error(span, "`let` variable name expected"));
+        p.advance_with_error();
+    }
+
+    if p.peek() == TokenKind::Equal {
+        p.advance();
+    } else {
+        let span = p.span();
+        p.emit(Diagnostic::error(span, "`=` expected after variable name"));
+        p.advance_with_error();
+    }
+
+    expr(p);
+
+    if p.peek() == TokenKind::Newline {
+        p.advance();
+    } else {
+        let span = p.span();
+        p.emit(Diagnostic::error(
+            span,
+            "new line expected after `let` expression",
+        ));
+        p.advance_with_error();
+    }
+
+    expr(p);
+
+    p.close(o, NodeKind::Let)
+}
+
 const PREFIX_TOKENS: TokenKindSet = TokenKindSet::new(&[
     TokenKind::Ident,
     TokenKind::Tag,
     TokenKind::Number,
     TokenKind::Color,
+    // NOTE: This is ambiguous in function calls.
+    // In that case, the infix operator takes precedence (because the `match` arms for the infix op
+    // come first.)
     TokenKind::Minus,
     TokenKind::Not,
     TokenKind::LParen,
@@ -614,8 +623,8 @@ fn prefix(p: &mut Parser) -> Closed {
     }
 }
 
-fn infix(p: &mut Parser, op: (TokenKind, Spaces)) -> NodeKind {
-    match op.0 {
+fn infix(p: &mut Parser, op: TokenKind) -> NodeKind {
+    match op {
         TokenKind::Plus
         | TokenKind::Minus
         | TokenKind::Star
@@ -630,13 +639,13 @@ fn infix(p: &mut Parser, op: (TokenKind, Spaces)) -> NodeKind {
 
         TokenKind::Equal => infix_let(p, op),
 
-        _ if PREFIX_TOKENS.contains(op.0) => infix_call(p, op),
+        _ if PREFIX_TOKENS.contains(op) => infix_call(p),
 
         _ => panic!("unhandled infix operator {op:?}"),
     }
 }
 
-fn infix_binary(p: &mut Parser, op: (TokenKind, Spaces)) -> NodeKind {
+fn infix_binary(p: &mut Parser, op: TokenKind) -> NodeKind {
     let o = p.open();
     p.advance();
     p.close(o, NodeKind::Op);
@@ -649,16 +658,15 @@ fn infix_binary(p: &mut Parser, op: (TokenKind, Spaces)) -> NodeKind {
     NodeKind::Binary
 }
 
-fn infix_call(p: &mut Parser, mut arg: (TokenKind, Spaces)) -> NodeKind {
+fn infix_call(p: &mut Parser) -> NodeKind {
     while PREFIX_TOKENS.contains(p.peek()) {
-        precedence_parse(p, arg);
-        arg = p.peek_with_spaces();
+        prefix(p);
     }
 
     NodeKind::Call
 }
 
-fn infix_let(p: &mut Parser, op: (TokenKind, Spaces)) -> NodeKind {
+fn infix_let(p: &mut Parser, op: TokenKind) -> NodeKind {
     p.advance();
 
     if p.peek() == TokenKind::Newline {
@@ -684,7 +692,7 @@ fn infix_let(p: &mut Parser, op: (TokenKind, Spaces)) -> NodeKind {
 }
 
 pub fn expr(p: &mut Parser) {
-    precedence_parse(p, (TokenKind::Eof, Spaces::new(true, false)))
+    precedence_parse(p, TokenKind::Eof)
 }
 
 pub fn toplevel(p: &mut Parser) {
diff --git a/crates/haku/src/token.rs b/crates/haku/src/token.rs
index c613408..5a0ba1f 100644
--- a/crates/haku/src/token.rs
+++ b/crates/haku/src/token.rs
@@ -1,7 +1,4 @@
-use core::{
-    error::Error,
-    fmt::{self, Display},
-};
+use core::{error::Error, fmt::Display};
 
 use alloc::vec::Vec;
 
@@ -52,16 +49,10 @@ pub enum TokenKind {
     Error,
 }
 
-#[derive(Clone, Copy, PartialEq, Eq)]
-pub struct Spaces {
-    value: u8, // 0b10 = left, 0b01 = right
-}
-
 #[derive(Debug, Clone)]
 pub struct Lexis {
-    kinds: Vec<TokenKind>,
-    spaces: Vec<Spaces>,
-    spans: Vec<Span>,
+    pub kinds: Vec<TokenKind>,
+    pub spans: Vec<Span>,
 }
 
 impl Lexis {
@@ -70,7 +61,6 @@ impl Lexis {
 
         Self {
             kinds: Vec::with_capacity(capacity),
-            spaces: Vec::with_capacity(capacity),
             spans: Vec::with_capacity(capacity),
         }
     }
@@ -83,18 +73,12 @@ impl Lexis {
         self.len() == 0
     }
 
-    pub fn push(
-        &mut self,
-        kind: TokenKind,
-        spaces: Spaces,
-        span: Span,
-    ) -> Result<(), TokenAllocError> {
+    pub fn push(&mut self, kind: TokenKind, span: Span) -> Result<(), TokenAllocError> {
         if self.kinds.len() >= self.kinds.capacity() {
             return Err(TokenAllocError);
         }
 
         self.kinds.push(kind);
-        self.spaces.push(spaces);
         self.spans.push(span);
 
         Ok(())
@@ -104,48 +88,11 @@ impl Lexis {
         self.kinds[position as usize]
     }
 
-    pub fn spaces(&self, position: u32) -> Spaces {
-        self.spaces[position as usize]
-    }
-
-    pub fn set_spaces(&mut self, position: u32, spaces: Spaces) {
-        self.spaces[position as usize] = spaces;
-    }
-
     pub fn span(&self, position: u32) -> Span {
         self.spans[position as usize]
     }
 }
 
-impl Spaces {
-    pub fn new(left: bool, right: bool) -> Self {
-        Self {
-            value: (left as u8) << 1 | right as u8,
-        }
-    }
-
-    pub fn left(self) -> bool {
-        (self.value & 0b10) == 0b10
-    }
-
-    pub fn right(self) -> bool {
-        (self.value & 0b01) == 0b01
-    }
-
-    pub fn pair(self) -> (bool, bool) {
-        (self.left(), self.right())
-    }
-}
-
-impl fmt::Debug for Spaces {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_tuple("Spaces")
-            .field(&self.left())
-            .field(&self.right())
-            .finish()
-    }
-}
-
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub struct TokenAllocError;
 
diff --git a/crates/rkgk/src/wall/database.rs b/crates/rkgk/src/wall/database.rs
index 8850c9c..3e146c0 100644
--- a/crates/rkgk/src/wall/database.rs
+++ b/crates/rkgk/src/wall/database.rs
@@ -81,6 +81,11 @@ impl Database {
 pub fn start(settings: Settings) -> eyre::Result<Database> {
     let db = Connection::open(settings.path).context("cannot open wall database")?;
 
+    let major: u32 = env!("CARGO_PKG_VERSION_MAJOR").parse().unwrap();
+    let minor: u32 = env!("CARGO_PKG_VERSION_MINOR").parse().unwrap();
+    let patch: u32 = env!("CARGO_PKG_VERSION_PATCH").parse().unwrap();
+    let version = major * 1_000_000 + minor * 1_000 + patch;
+
     info!("initial setup");
 
     let version: u32 = db.pragma_query_value(None, "user_version", |x| x.get(0))?;
@@ -105,7 +110,7 @@ pub fn start(settings: Settings) -> eyre::Result<Database> {
                 paint_area   INTEGER NOT NULL,
                 chunk_size   INTEGER NOT NULL
             );
-
+        
             CREATE TABLE IF NOT EXISTS
             t_wall_info (
                 id         INTEGER PRIMARY KEY CHECK (id = 1),
diff --git a/static/brush-box.js b/static/brush-box.js
index dfcc850..92d01d7 100644
--- a/static/brush-box.js
+++ b/static/brush-box.js
@@ -45,8 +45,8 @@ or_: \\a, b ->
   else b
 
 withDotter \\d ->
-  visible? = mod (d Num) length < length * duty
-  if (visible?)
+  visible = mod (d Num) length < length * duty
+  if (visible)
     stroke thickness color (line (d From) (d To))
   else
     ()
@@ -76,9 +76,9 @@ wavelength: 1
 
 withDotter \\d ->
   pi = 3.14159265
-  a = sin (d Num * wavelength / pi) + 1 / 2
+  a = (sin (d Num * wavelength / pi) + 1) / 2
   range = maxThickness - minThickness
-  thickness = a * range + minThickness
+  thickness = minThickness + a * range
   stroke thickness color (line (d From) (d To))
         `.trim(),
     },
diff --git a/static/haku.js b/static/haku.js
index a9532d0..69d1b0f 100644
--- a/static/haku.js
+++ b/static/haku.js
@@ -217,14 +217,9 @@ export class Haku {
         console.groupCollapsed("construct Haku");
         {
             let pLimits = allocCheck(w.haku_limits_new());
-            w.haku_limits_set_max_source_code_len(pLimits, limits.max_source_code_len);
-            w.haku_limits_set_max_chunks(pLimits, limits.max_chunks);
-            w.haku_limits_set_max_defs(pLimits, limits.max_defs);
-            w.haku_limits_set_max_tags(pLimits, limits.max_tags);
-            w.haku_limits_set_max_tokens(pLimits, limits.max_tokens);
-            w.haku_limits_set_max_parser_events(pLimits, limits.max_parser_events);
-            w.haku_limits_set_ast_capacity(pLimits, limits.ast_capacity);
-            w.haku_limits_set_chunk_capacity(pLimits, limits.chunk_capacity);
+            for (let name of Object.keys(limits)) {
+                w[`haku_limits_set_${name}`](pLimits, limits[name]);
+            }
 
             this.#pInstance = allocCheck(w.haku_instance_new(pLimits));
 
diff --git a/static/painter.js b/static/painter.js
index 4bdfa94..2e9b067 100644
--- a/static/painter.js
+++ b/static/painter.js
@@ -55,6 +55,10 @@ export function selfController(interactionQueue, wall, layer, event) {
             if (renderArea != null) {
                 let numChunksToRender = numChunksInRectangle(renderArea, layer.chunkSize);
                 let result = renderToChunksInArea(layer, renderArea, renderToPixmap);
+                if (!layer.canFitNewChunks(numChunksToRender)) {
+                    console.debug("too many chunks rendered; committing interaction early");
+                    event.earlyCommitInteraction();
+                }
                 return result;
             } else {
                 console.debug("render area is empty, nothing will be rendered");