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+// Test closures.
+
+--- closure-without-params-non-atomic ---
+// Don't parse closure directly in content.
+
+#let x = "x"
+
+// Should output `x => y`.
+#x => y
+
+--- closure-without-captures ---
+// Basic closure without captures.
+#{
+  let adder = (x, y) => x + y
+  test(adder(2, 3), 5)
+}
+
+--- closure-as-arg ---
+// Pass closure as argument and return closure.
+// Also uses shorthand syntax for a single argument.
+#{
+  let chain = (f, g) => (x) => f(g(x))
+  let f = x => x + 1
+  let g = x => 2 * x
+  let h = chain(f, g)
+  test(h(2), 5)
+}
+
+--- closure-capture-from-popped-stack-frame ---
+// Capture environment.
+#{
+  let mark = "!"
+  let greet = {
+    let hi = "Hi"
+    name => {
+        hi + ", " + name + mark
+    }
+  }
+
+  test(greet("Typst"), "Hi, Typst!")
+
+  // Changing the captured variable after the closure definition has no effect.
+  mark = "?"
+  test(greet("Typst"), "Hi, Typst!")
+}
+
+--- closure-shadows-outer-var ---
+// Redefined variable.
+#{
+  let x = 1
+  let f() = {
+    let x = x + 2
+    x
+  }
+  test(f(), 3)
+}
+
+--- closure-shadows-outer-var-import ---
+// Import bindings.
+#{
+  let b = "module.typ"
+  let f() = {
+    import b: b
+    b
+  }
+  test(f(), 1)
+}
+
+--- closure-shadows-outer-var-for-loop ---
+// For loop bindings.
+#{
+  let v = (1, 2, 3)
+  let f() = {
+    let s = 0
+    for v in v { s += v }
+    s
+  }
+  test(f(), 6)
+}
+
+--- closure-let-basic ---
+// Let + closure bindings.
+#{
+  let g = "hi"
+  let f() = {
+    let g() = "bye"
+    g()
+  }
+  test(f(), "bye")
+}
+
+--- closure-let-args ---
+// Parameter bindings.
+#{
+  let x = 5
+  let g() = {
+    let f(x, y: x) = x + y
+    f
+  }
+
+  test(g()(8), 13)
+}
+
+--- closure-bad-capture ---
+// Don't leak environment.
+#{
+  // Error: 16-17 unknown variable: x
+  let func() = x
+  let x = "hi"
+  func()
+}
+
+--- closure-missing-arg-positional ---
+// Too few arguments.
+#{
+  let types(x, y) = "[" + str(type(x)) + ", " + str(type(y)) + "]"
+  test(types(14%, 12pt), "[ratio, length]")
+
+  // Error: 8-21 missing argument: y
+  test(types("nope"), "[string, none]")
+}
+
+--- closure-too-many-args-positional ---
+// Too many arguments.
+#{
+  let f(x) = x + 1
+
+  // Error: 8-13 unexpected argument
+  f(1, "two", () => x)
+}
+
+--- closure-capture-in-lvalue ---
+// Mutable method with capture in argument.
+#let x = "b"
+#let f() = {
+  let a = (b: 5)
+  a.at(x) = 10
+  a
+}
+#f()
+
+--- closure-capture-mutate ---
+#let x = ()
+#let f() = {
+  // Error: 3-4 variables from outside the function are read-only and cannot be modified
+  x.at(1) = 2
+}
+#f()
+
+--- closure-named-args-basic ---
+// Named arguments.
+#{
+  let greet(name, birthday: false) = {
+    if birthday { "Happy Birthday, " } else { "Hey, " } + name + "!"
+  }
+
+  test(greet("Typst"), "Hey, Typst!")
+  test(greet("Typst", birthday: true), "Happy Birthday, Typst!")
+
+  // Error: 23-35 unexpected argument: whatever
+  test(greet("Typst", whatever: 10))
+}
+
+--- closure-args-sink ---
+// Parameter unpacking.
+#let f((a, b), ..c) = (a, b, c)
+#test(f((1, 2), 3, 4), (1, 2, (3, 4)))
+
+#let f((k: a, b), c: 3, (d,)) = (a, b, c, d)
+#test(f((k: 1, b: 2), (4,)), (1, 2, 3, 4))
+
+// Error: 8-14 expected identifier, found destructuring pattern
+#let f((a, b): 0) = none
+
+// Error: 10-19 expected pattern, found array
+#let f(..(a, b: c)) = none
+
+// Error: 10-16 expected pattern, found array
+#let f(..(a, b)) = none
+
+--- closure-param-duplicate-positional ---
+// Error: 11-12 duplicate parameter: x
+#let f(x, x) = none
+
+--- closure-body-multiple-expressions ---
+// Error: 21 expected comma
+// Error: 22-23 expected pattern, found integer
+// Error: 24-25 unexpected plus
+// Error: 26-27 expected pattern, found integer
+#let f = (x: () => 1 2 + 3) => 4
+
+--- closure-param-duplicate-mixed ---
+// Error: 14-15 duplicate parameter: a
+// Error: 23-24 duplicate parameter: b
+// Error: 35-36 duplicate parameter: b
+#let f(a, b, a: none, b: none, c, b) = none
+
+--- closure-param-duplicate-spread ---
+// Error: 13-14 duplicate parameter: a
+#let f(a, ..a) = none
+
+--- closure-pattern-bad-string ---
+// Error: 7-14 expected pattern, found string
+#((a, "named": b) => none)
+
+--- closure-let-pattern-bad-string ---
+// Error: 10-15 expected pattern, found string
+#let foo("key": b) = key
+
+--- closure-param-keyword ---
+// Error: 10-14 expected pattern, found `none`
+// Hint: 10-14 keyword `none` is not allowed as an identifier; try `none_` instead
+#let foo(none: b) = key
+
+--- closure-param-named-underscore ---
+// Error: 10-11 expected identifier, found underscore
+#let foo(_: 3) = none
+
+--- issue-non-atomic-closure ---
+// Ensure that we can't have non-atomic closures.
+#let x = 1
+#let c = [#(x) => (1, 2)]
+#test(c.children.last(), [(1, 2)]))