Support for generating native functions at runtime

crates/typst-html/src/encode.rs

@@ -69,6 +69,10 @@ fn write_element(w: &mut Writer, element: &HtmlElement) -> SourceResult<()> {
     for (attr, value) in &element.attrs.0 {
         w.buf.push(' ');
         w.buf.push_str(&attr.resolve());
+
+        // If the string is empty, we can use shorthand syntax.
+        // `<elem attr="">..</div` is equivalent to `<elem attr>..</div>`
+        if !value.is_empty() {
             w.buf.push('=');
             w.buf.push('"');
             for c in value.chars() {
@@ -80,6 +84,7 @@ fn write_element(w: &mut Writer, element: &HtmlElement) -> SourceResult<()> {
             }
             w.buf.push('"');
         }
+    }
 
     w.buf.push('>');
 

crates/typst-library/src/foundations/duration.rs

@@ -16,6 +16,21 @@ impl Duration {
     pub fn is_zero(&self) -> bool {
         self.0.is_zero()
     }
+
+    /// Decomposes the time into whole weeks, days, hours, minutes, and seconds.
+    pub fn decompose(&self) -> [i64; 5] {
+        let mut tmp = self.0;
+        let weeks = tmp.whole_weeks();
+        tmp -= weeks.weeks();
+        let days = tmp.whole_days();
+        tmp -= days.days();
+        let hours = tmp.whole_hours();
+        tmp -= hours.hours();
+        let minutes = tmp.whole_minutes();
+        tmp -= minutes.minutes();
+        let seconds = tmp.whole_seconds();
+        [weeks, days, hours, minutes, seconds]
+    }
 }
 
 #[scope]
@@ -118,34 +133,25 @@ impl Debug for Duration {
 
 impl Repr for Duration {
     fn repr(&self) -> EcoString {
-        let mut tmp = self.0;
+        let [weeks, days, hours, minutes, seconds] = self.decompose();
         let mut vec = Vec::with_capacity(5);
 
-        let weeks = tmp.whole_seconds() / 604_800.0 as i64;
         if weeks != 0 {
             vec.push(eco_format!("weeks: {}", weeks.repr()));
         }
-        tmp -= weeks.weeks();
 
-        let days = tmp.whole_days();
         if days != 0 {
             vec.push(eco_format!("days: {}", days.repr()));
         }
-        tmp -= days.days();
 
-        let hours = tmp.whole_hours();
         if hours != 0 {
             vec.push(eco_format!("hours: {}", hours.repr()));
         }
-        tmp -= hours.hours();
 
-        let minutes = tmp.whole_minutes();
         if minutes != 0 {
             vec.push(eco_format!("minutes: {}", minutes.repr()));
         }
-        tmp -= minutes.minutes();
 
-        let seconds = tmp.whole_seconds();
         if seconds != 0 {
             vec.push(eco_format!("seconds: {}", seconds.repr()));
         }

crates/typst-library/src/foundations/func.rs

@@ -307,7 +307,7 @@ impl Func {
     ) -> SourceResult<Value> {
         match &self.repr {
             Repr::Native(native) => {
-                let value = (native.function)(engine, context, &mut args)?;
+                let value = (native.function.0)(engine, context, &mut args)?;
                 args.finish()?;
                 Ok(value)
             }
@@ -491,8 +491,8 @@ pub trait NativeFunc {
 /// Defines a native function.
 #[derive(Debug)]
 pub struct NativeFuncData {
-    /// Invokes the function from Typst.
-    pub function: fn(&mut Engine, Tracked<Context>, &mut Args) -> SourceResult<Value>,
+    /// The implementation of the function.
+    pub function: NativeFuncPtr,
     /// The function's normal name (e.g. `align`), as exposed to Typst.
     pub name: &'static str,
     /// The function's title case name (e.g. `Align`).
@@ -504,11 +504,11 @@ pub struct NativeFuncData {
     /// Whether this function makes use of context.
     pub contextual: bool,
     /// Definitions in the scope of the function.
-    pub scope: LazyLock<Scope>,
+    pub scope: DynLazyLock<Scope>,
     /// A list of parameter information for each parameter.
-    pub params: LazyLock<Vec<ParamInfo>>,
+    pub params: DynLazyLock<Vec<ParamInfo>>,
     /// Information about the return value of this function.
-    pub returns: LazyLock<CastInfo>,
+    pub returns: DynLazyLock<CastInfo>,
 }
 
 cast! {
@@ -516,6 +516,28 @@ cast! {
     self => Func::from(self).into_value(),
 }
 
+/// A pointer to a native function's implementation.
+pub struct NativeFuncPtr(pub &'static NativeFuncSignature);
+
+/// The signature of a native function's implementation.
+type NativeFuncSignature =
+    dyn Fn(&mut Engine, Tracked<Context>, &mut Args) -> SourceResult<Value> + Send + Sync;
+
+impl Debug for NativeFuncPtr {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        f.pad("NativeFuncPtr(..)")
+    }
+}
+
+/// A `LazyLock` that uses a static closure for initialization instead of only
+/// working with function pointers.
+///
+/// Can be created from a normal function or closure by prepending with a `&`,
+/// e.g. `LazyLock::new(&|| "hello")`. Can be created from a dynamic closure
+/// by allocating and then leaking it. This is equivalent to having it
+/// statically allocated, but allows for it to be generated at runtime.
+type DynLazyLock<T> = LazyLock<T, &'static (dyn Fn() -> T + Send + Sync)>;
+
 /// Describes a function parameter.
 #[derive(Debug, Clone)]
 pub struct ParamInfo {

crates/typst-library/src/layout/axes.rs

@@ -4,9 +4,12 @@ use std::ops::{BitAnd, BitAndAssign, BitOr, BitOrAssign, Deref, Not};
 
 use typst_utils::Get;
 
-use crate::diag::bail;
-use crate::foundations::{array, cast, Array, Resolve, Smart, StyleChain};
-use crate::layout::{Abs, Dir, Length, Ratio, Rel, Size};
+use crate::diag::{bail, HintedStrResult};
+use crate::foundations::{
+    array, cast, Array, CastInfo, FromValue, IntoValue, Reflect, Resolve, Smart,
+    StyleChain, Value,
+};
+use crate::layout::{Abs, Dir, Rel, Size};
 
 /// A container with a horizontal and vertical component.
 #[derive(Default, Copy, Clone, Eq, PartialEq, Hash)]
@@ -275,40 +278,39 @@ impl BitAndAssign for Axes<bool> {
     }
 }
 
-cast! {
-    Axes<Rel<Length>>,
-    self => array![self.x, self.y].into_value(),
-    array: Array => {
-        let mut iter = array.into_iter();
-        match (iter.next(), iter.next(), iter.next()) {
-            (Some(a), Some(b), None) => Axes::new(a.cast()?, b.cast()?),
-            _ => bail!("point array must contain exactly two entries"),
-        }
-    },
+impl<T: Reflect> Reflect for Axes<T> {
+    fn input() -> CastInfo {
+        Array::input()
     }
 
-cast! {
-    Axes<Ratio>,
-    self => array![self.x, self.y].into_value(),
-    array: Array => {
-        let mut iter = array.into_iter();
-        match (iter.next(), iter.next(), iter.next()) {
-            (Some(a), Some(b), None) => Axes::new(a.cast()?, b.cast()?),
-            _ => bail!("ratio array must contain exactly two entries"),
-        }
-    },
+    fn output() -> CastInfo {
+        Array::output()
     }
 
-cast! {
-    Axes<Length>,
-    self => array![self.x, self.y].into_value(),
-    array: Array => {
+    fn castable(value: &Value) -> bool {
+        Array::castable(value)
+    }
+}
+
+impl<T: FromValue> FromValue for Axes<T> {
+    fn from_value(value: Value) -> HintedStrResult<Self> {
+        let array = value.cast::<Array>()?;
         let mut iter = array.into_iter();
         match (iter.next(), iter.next(), iter.next()) {
-            (Some(a), Some(b), None) => Axes::new(a.cast()?, b.cast()?),
-            _ => bail!("length array must contain exactly two entries"),
+            (Some(a), Some(b), None) => Ok(Axes::new(a.cast()?, b.cast()?)),
+            _ => bail!(
+                "array must contain exactly two items";
+                hint: "the first item determines the value for the X axis \
+                       and the second item the value for the Y axis"
+            ),
+        }
+    }
+}
+
+impl<T: IntoValue> IntoValue for Axes<T> {
+    fn into_value(self) -> Value {
+        array![self.x.into_value(), self.y.into_value()].into_value()
     }
-    },
 }
 
 impl<T: Resolve> Resolve for Axes<T> {

crates/typst-library/src/text/raw.rs

@@ -836,7 +836,7 @@ fn to_typst(synt::Color { r, g, b, a }: synt::Color) -> Color {
 }
 
 fn to_syn(color: Color) -> synt::Color {
-    let [r, g, b, a] = color.to_rgb().to_vec4_u8();
+    let (r, g, b, a) = color.to_rgb().into_format::<u8, u8>().into_components();
     synt::Color { r, g, b, a }
 }
 

crates/typst-library/src/visualize/color.rs

@@ -262,7 +262,7 @@ impl Color {
         color: Color,
     ) -> SourceResult<Color> {
         Ok(if let Some(color) = args.find::<Color>()? {
-            color.to_luma()
+            Color::Luma(color.to_luma())
         } else {
             let Component(gray) =
                 args.expect("gray component").unwrap_or(Component(Ratio::one()));
@@ -318,7 +318,7 @@ impl Color {
         color: Color,
     ) -> SourceResult<Color> {
         Ok(if let Some(color) = args.find::<Color>()? {
-            color.to_oklab()
+            Color::Oklab(color.to_oklab())
         } else {
             let RatioComponent(l) = args.expect("lightness component")?;
             let ChromaComponent(a) = args.expect("A component")?;
@@ -374,7 +374,7 @@ impl Color {
         color: Color,
     ) -> SourceResult<Color> {
         Ok(if let Some(color) = args.find::<Color>()? {
-            color.to_oklch()
+            Color::Oklch(color.to_oklch())
         } else {
             let RatioComponent(l) = args.expect("lightness component")?;
             let ChromaComponent(c) = args.expect("chroma component")?;
@@ -434,7 +434,7 @@ impl Color {
         color: Color,
     ) -> SourceResult<Color> {
         Ok(if let Some(color) = args.find::<Color>()? {
-            color.to_linear_rgb()
+            Color::LinearRgb(color.to_linear_rgb())
         } else {
             let Component(r) = args.expect("red component")?;
             let Component(g) = args.expect("green component")?;
@@ -505,7 +505,7 @@ impl Color {
         Ok(if let Some(string) = args.find::<Spanned<Str>>()? {
             Self::from_str(&string.v).at(string.span)?
         } else if let Some(color) = args.find::<Color>()? {
-            color.to_rgb()
+            Color::Rgb(color.to_rgb())
         } else {
             let Component(r) = args.expect("red component")?;
             let Component(g) = args.expect("green component")?;
@@ -565,7 +565,7 @@ impl Color {
         color: Color,
     ) -> SourceResult<Color> {
         Ok(if let Some(color) = args.find::<Color>()? {
-            color.to_cmyk()
+            Color::Cmyk(color.to_cmyk())
         } else {
             let RatioComponent(c) = args.expect("cyan component")?;
             let RatioComponent(m) = args.expect("magenta component")?;
@@ -622,7 +622,7 @@ impl Color {
         color: Color,
     ) -> SourceResult<Color> {
         Ok(if let Some(color) = args.find::<Color>()? {
-            color.to_hsl()
+            Color::Hsl(color.to_hsl())
         } else {
             let h: Angle = args.expect("hue component")?;
             let Component(s) = args.expect("saturation component")?;
@@ -679,7 +679,7 @@ impl Color {
         color: Color,
     ) -> SourceResult<Color> {
         Ok(if let Some(color) = args.find::<Color>()? {
-            color.to_hsv()
+            Color::Hsv(color.to_hsv())
         } else {
             let h: Angle = args.expect("hue component")?;
             let Component(s) = args.expect("saturation component")?;
@@ -830,7 +830,7 @@ impl Color {
     /// omitted if it is equal to `ff` (255 / 100%).
     #[func]
     pub fn to_hex(self) -> EcoString {
-        let [r, g, b, a] = self.to_rgb().to_vec4_u8();
+        let (r, g, b, a) = self.to_rgb().into_format::<u8, u8>().into_components();
         if a != 255 {
             eco_format!("#{:02x}{:02x}{:02x}{:02x}", r, g, b, a)
         } else {
@@ -886,20 +886,21 @@ impl Color {
         /// The factor to saturate the color by.
         factor: Ratio,
     ) -> SourceResult<Color> {
+        let f = factor.get() as f32;
         Ok(match self {
-            Self::Luma(_) => {
-                bail!(
+            Self::Luma(_) => bail!(
                 span, "cannot saturate grayscale color";
                 hint: "try converting your color to RGB first"
-                );
+            ),
+            Self::Hsl(c) => Self::Hsl(c.saturate(f)),
+            Self::Hsv(c) => Self::Hsv(c.saturate(f)),
+            Self::Oklab(_)
+            | Self::Oklch(_)
+            | Self::LinearRgb(_)
+            | Self::Rgb(_)
+            | Self::Cmyk(_) => {
+                Color::Hsv(self.to_hsv().saturate(f)).to_space(self.space())
             }
-            Self::Oklab(_) => self.to_hsv().saturate(span, factor)?.to_oklab(),
-            Self::Oklch(_) => self.to_hsv().saturate(span, factor)?.to_oklch(),
-            Self::LinearRgb(_) => self.to_hsv().saturate(span, factor)?.to_linear_rgb(),
-            Self::Rgb(_) => self.to_hsv().saturate(span, factor)?.to_rgb(),
-            Self::Cmyk(_) => self.to_hsv().saturate(span, factor)?.to_cmyk(),
-            Self::Hsl(c) => Self::Hsl(c.saturate(factor.get() as f32)),
-            Self::Hsv(c) => Self::Hsv(c.saturate(factor.get() as f32)),
         })
     }
 
@@ -911,20 +912,21 @@ impl Color {
         /// The factor to desaturate the color by.
         factor: Ratio,
     ) -> SourceResult<Color> {
+        let f = factor.get() as f32;
         Ok(match self {
-            Self::Luma(_) => {
-                bail!(
+            Self::Luma(_) => bail!(
                 span, "cannot desaturate grayscale color";
                 hint: "try converting your color to RGB first"
-                );
+            ),
+            Self::Hsl(c) => Self::Hsl(c.desaturate(f)),
+            Self::Hsv(c) => Self::Hsv(c.desaturate(f)),
+            Self::Oklab(_)
+            | Self::Oklch(_)
+            | Self::LinearRgb(_)
+            | Self::Rgb(_)
+            | Self::Cmyk(_) => {
+                Color::Hsv(self.to_hsv().desaturate(f)).to_space(self.space())
             }
-            Self::Oklab(_) => self.to_hsv().desaturate(span, factor)?.to_oklab(),
-            Self::Oklch(_) => self.to_hsv().desaturate(span, factor)?.to_oklch(),
-            Self::LinearRgb(_) => self.to_hsv().desaturate(span, factor)?.to_linear_rgb(),
-            Self::Rgb(_) => self.to_hsv().desaturate(span, factor)?.to_rgb(),
-            Self::Cmyk(_) => self.to_hsv().desaturate(span, factor)?.to_cmyk(),
-            Self::Hsl(c) => Self::Hsl(c.desaturate(factor.get() as f32)),
-            Self::Hsv(c) => Self::Hsv(c.desaturate(factor.get() as f32)),
         })
     }
 
@@ -994,23 +996,17 @@ impl Color {
     ) -> SourceResult<Color> {
         Ok(match space {
             ColorSpace::Oklch => {
-                let Self::Oklch(oklch) = self.to_oklch() else {
-                    unreachable!();
-                };
+                let oklch = self.to_oklch();
                 let rotated = oklch.shift_hue(angle.to_deg() as f32);
                 Self::Oklch(rotated).to_space(self.space())
             }
             ColorSpace::Hsl => {
-                let Self::Hsl(hsl) = self.to_hsl() else {
-                    unreachable!();
-                };
+                let hsl = self.to_hsl();
                 let rotated = hsl.shift_hue(angle.to_deg() as f32);
                 Self::Hsl(rotated).to_space(self.space())
             }
             ColorSpace::Hsv => {
-                let Self::Hsv(hsv) = self.to_hsv() else {
-                    unreachable!();
-                };
+                let hsv = self.to_hsv();
                 let rotated = hsv.shift_hue(angle.to_deg() as f32);
                 Self::Hsv(rotated).to_space(self.space())
             }
@@ -1281,19 +1277,19 @@ impl Color {
 
     pub fn to_space(self, space: ColorSpace) -> Self {
         match space {
-            ColorSpace::Oklab => self.to_oklab(),
-            ColorSpace::Oklch => self.to_oklch(),
-            ColorSpace::Srgb => self.to_rgb(),
-            ColorSpace::LinearRgb => self.to_linear_rgb(),
-            ColorSpace::Hsl => self.to_hsl(),
-            ColorSpace::Hsv => self.to_hsv(),
-            ColorSpace::Cmyk => self.to_cmyk(),
-            ColorSpace::D65Gray => self.to_luma(),
+            ColorSpace::D65Gray => Self::Luma(self.to_luma()),
+            ColorSpace::Oklab => Self::Oklab(self.to_oklab()),
+            ColorSpace::Oklch => Self::Oklch(self.to_oklch()),
+            ColorSpace::Srgb => Self::Rgb(self.to_rgb()),
+            ColorSpace::LinearRgb => Self::LinearRgb(self.to_linear_rgb()),
+            ColorSpace::Cmyk => Self::Cmyk(self.to_cmyk()),
+            ColorSpace::Hsl => Self::Hsl(self.to_hsl()),
+            ColorSpace::Hsv => Self::Hsv(self.to_hsv()),
         }
     }
 
-    pub fn to_luma(self) -> Self {
-        Self::Luma(match self {
+    pub fn to_luma(self) -> Luma {
+        match self {
             Self::Luma(c) => c,
             Self::Oklab(c) => Luma::from_color(c),
             Self::Oklch(c) => Luma::from_color(c),
@@ -1302,11 +1298,11 @@ impl Color {
             Self::Cmyk(c) => Luma::from_color(c.to_rgba()),
             Self::Hsl(c) => Luma::from_color(c),
             Self::Hsv(c) => Luma::from_color(c),
-        })
+        }
     }
 
-    pub fn to_oklab(self) -> Self {
-        Self::Oklab(match self {
+    pub fn to_oklab(self) -> Oklab {
+        match self {
             Self::Luma(c) => Oklab::from_color(c),
             Self::Oklab(c) => c,
             Self::Oklch(c) => Oklab::from_color(c),
@@ -1315,11 +1311,11 @@ impl Color {
             Self::Cmyk(c) => Oklab::from_color(c.to_rgba()),
             Self::Hsl(c) => Oklab::from_color(c),
             Self::Hsv(c) => Oklab::from_color(c),
-        })
+        }
     }
 
-    pub fn to_oklch(self) -> Self {
-        Self::Oklch(match self {
+    pub fn to_oklch(self) -> Oklch {
+        match self {
             Self::Luma(c) => Oklch::from_color(c),
             Self::Oklab(c) => Oklch::from_color(c),
             Self::Oklch(c) => c,
@@ -1328,11 +1324,11 @@ impl Color {
             Self::Cmyk(c) => Oklch::from_color(c.to_rgba()),
             Self::Hsl(c) => Oklch::from_color(c),
             Self::Hsv(c) => Oklch::from_color(c),
-        })
+        }
     }
 
-    pub fn to_rgb(self) -> Self {
-        Self::Rgb(match self {
+    pub fn to_rgb(self) -> Rgb {
+        match self {
             Self::Luma(c) => Rgb::from_color(c),
             Self::Oklab(c) => Rgb::from_color(c),
             Self::Oklch(c) => Rgb::from_color(c),
@@ -1341,11 +1337,11 @@ impl Color {
             Self::Cmyk(c) => Rgb::from_color(c.to_rgba()),
             Self::Hsl(c) => Rgb::from_color(c),
             Self::Hsv(c) => Rgb::from_color(c),
-        })
+        }
     }
 
-    pub fn to_linear_rgb(self) -> Self {
-        Self::LinearRgb(match self {
+    pub fn to_linear_rgb(self) -> LinearRgb {
+        match self {
             Self::Luma(c) => LinearRgb::from_color(c),
             Self::Oklab(c) => LinearRgb::from_color(c),
             Self::Oklch(c) => LinearRgb::from_color(c),
@@ -1354,11 +1350,11 @@ impl Color {
             Self::Cmyk(c) => LinearRgb::from_color(c.to_rgba()),
             Self::Hsl(c) => Rgb::from_color(c).into_linear(),
             Self::Hsv(c) => Rgb::from_color(c).into_linear(),
-        })
+        }
     }
 
-    pub fn to_cmyk(self) -> Self {
-        Self::Cmyk(match self {
+    pub fn to_cmyk(self) -> Cmyk {
+        match self {
             Self::Luma(c) => Cmyk::from_luma(c),
             Self::Oklab(c) => Cmyk::from_rgba(Rgb::from_color(c)),
             Self::Oklch(c) => Cmyk::from_rgba(Rgb::from_color(c)),
@@ -1367,11 +1363,11 @@ impl Color {
             Self::Cmyk(c) => c,
             Self::Hsl(c) => Cmyk::from_rgba(Rgb::from_color(c)),
             Self::Hsv(c) => Cmyk::from_rgba(Rgb::from_color(c)),
-        })
+        }
     }
 
-    pub fn to_hsl(self) -> Self {
-        Self::Hsl(match self {
+    pub fn to_hsl(self) -> Hsl {
+        match self {
             Self::Luma(c) => Hsl::from_color(c),
             Self::Oklab(c) => Hsl::from_color(c),
             Self::Oklch(c) => Hsl::from_color(c),
@@ -1380,11 +1376,11 @@ impl Color {
             Self::Cmyk(c) => Hsl::from_color(c.to_rgba()),
             Self::Hsl(c) => c,
             Self::Hsv(c) => Hsl::from_color(c),
-        })
+        }
     }
 
-    pub fn to_hsv(self) -> Self {
-        Self::Hsv(match self {
+    pub fn to_hsv(self) -> Hsv {
+        match self {
             Self::Luma(c) => Hsv::from_color(c),
             Self::Oklab(c) => Hsv::from_color(c),
             Self::Oklch(c) => Hsv::from_color(c),
@@ -1393,7 +1389,7 @@ impl Color {
             Self::Cmyk(c) => Hsv::from_color(c.to_rgba()),
             Self::Hsl(c) => Hsv::from_color(c),
             Self::Hsv(c) => c,
-        })
+        }
     }
 }
 

crates/typst-macros/src/func.rs

@@ -315,15 +315,15 @@ fn create_func_data(func: &Func) -> TokenStream {
 
     quote! {
         #foundations::NativeFuncData {
-            function: #closure,
+            function: #foundations::NativeFuncPtr(&#closure),
             name: #name,
             title: #title,
             docs: #docs,
             keywords: &[#(#keywords),*],
             contextual: #contextual,
-            scope: ::std::sync::LazyLock::new(|| #scope),
-            params: ::std::sync::LazyLock::new(|| ::std::vec![#(#params),*]),
-            returns:  ::std::sync::LazyLock::new(|| <#returns as #foundations::Reflect>::output()),
+            scope: ::std::sync::LazyLock::new(&|| #scope),
+            params: ::std::sync::LazyLock::new(&|| ::std::vec![#(#params),*]),
+            returns:  ::std::sync::LazyLock::new(&|| <#returns as #foundations::Reflect>::output()),
         }
     }
 }

crates/typst-render/src/paint.rs

@@ -255,13 +255,13 @@ pub fn to_sk_paint<'a>(
 }
 
 pub fn to_sk_color(color: Color) -> sk::Color {
-    let [r, g, b, a] = color.to_rgb().to_vec4();
+    let (r, g, b, a) = color.to_rgb().into_components();
     sk::Color::from_rgba(r, g, b, a)
         .expect("components must always be in the range [0..=1]")
 }
 
 pub fn to_sk_color_u8(color: Color) -> sk::ColorU8 {
-    let [r, g, b, a] = color.to_rgb().to_vec4_u8();
+    let (r, g, b, a) = color.to_rgb().into_format::<u8, u8>().into_components();
     sk::ColorU8::from_rgba(r, g, b, a)
 }
 

crates/typst-utils/src/lib.rs

@@ -23,7 +23,7 @@ pub use self::scalar::Scalar;
 #[doc(hidden)]
 pub use once_cell;
 
-use std::fmt::{Debug, Formatter};
+use std::fmt::{Debug, Display, Formatter};
 use std::hash::Hash;
 use std::iter::{Chain, Flatten, Rev};
 use std::num::{NonZeroU32, NonZeroUsize};
@@ -52,6 +52,25 @@ where
     Wrapper(f)
 }
 
+/// Turn a closure into a struct implementing [`Display`].
+pub fn display<F>(f: F) -> impl Display
+where
+    F: Fn(&mut Formatter) -> std::fmt::Result,
+{
+    struct Wrapper<F>(F);
+
+    impl<F> Display for Wrapper<F>
+    where
+        F: Fn(&mut Formatter) -> std::fmt::Result,
+    {
+        fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+            self.0(f)
+        }
+    }
+
+    Wrapper(f)
+}
+
 /// Calculate a 128-bit siphash of a value.
 pub fn hash128<T: Hash + ?Sized>(value: &T) -> u128 {
     let mut state = SipHasher13::new();

tests/suite/visualize/line.typ

@@ -84,7 +84,8 @@
 --- line-bad-point-array ---
 // Test errors.
 
-// Error: 12-19 point array must contain exactly two entries
+// Error: 12-19 array must contain exactly two items
+// Hint: 12-19 the first item determines the value for the X axis and the second item the value for the Y axis
 #line(end: (50pt,))
 
 --- line-bad-point-component-type ---

tests/suite/visualize/path.typ

@@ -76,7 +76,8 @@
 #path(((0%, 0%), (0%, 0%), (0%, 0%), (0%, 0%)))
 
 --- path-bad-point-array ---
-// Error: 7-31 point array must contain exactly two entries
+// Error: 7-31 array must contain exactly two items
+// Hint: 7-31 the first item determines the value for the X axis and the second item the value for the Y axis
 // Warning: 2-6 the `path` function is deprecated, use `curve` instead
 #path(((0%, 0%), (0%, 0%, 0%)))
 

tests/suite/visualize/polygon.typ

@@ -49,7 +49,8 @@
 )
 
 --- polygon-bad-point-array ---
-// Error: 10-17 point array must contain exactly two entries
+// Error: 10-17 array must contain exactly two items
+// Hint: 10-17 the first item determines the value for the X axis and the second item the value for the Y axis
 #polygon((50pt,))
 
 --- polygon-infinite-size ---