fix: fix bug of effect

src/configs.typ

@@ -333,6 +333,8 @@
 /// - uncover (function): The function to uncover content. The default value is `utils.uncover` function.
 ///
 /// - only (function): The function to show only the content. The default value is `utils.only` function.
+/// 
+/// - effect (function): The function to add effect to the content. The default value is `utils.effect`.
 ///
 /// - alternatives-match (function): The function to match alternatives. The default value is `utils.alternatives-match` function.
 ///
@@ -358,6 +360,7 @@
   // dynamic control
   uncover: _default,
   only: _default,
+  effect: _default,
   alternatives-match: _default,
   alternatives: _default,
   alternatives-fn: _default,
@@ -377,6 +380,7 @@
       cover: cover,
       uncover: uncover,
       only: only,
+      effect: effect,
       alternatives-match: alternatives-match,
       alternatives: alternatives,
       alternatives-fn: alternatives-fn,
@@ -656,6 +660,7 @@
     // dynamic control
     uncover: utils.uncover,
     only: utils.only,
+    effect: utils.effect,
     alternatives-match: utils.alternatives-match,
     alternatives: utils.alternatives,
     alternatives-fn: utils.alternatives-fn,

src/core.typ

@@ -511,7 +511,7 @@
 /// - cont (content): The content to display when the content is visible in the subslide.
 ///
 /// - is-method (boolean): A boolean indicating whether the function is a method function. Default is `false`. 
-#let effect(visible-subslides, fn, cont, is-method: false) = {
+#let effect(fn, visible-subslides, cont, is-method: false) = {
   touying-fn-wrapper(
     if is-method {
       fn

src/utils.typ

@@ -972,6 +972,38 @@
   }
 }
 
+/// Take effect in some subslides.
+/// 
+/// Example: `#effect(text.with(fill: red), "2-")[Something]` will display `[Something]` if the current slide is 2 or later.
+/// 
+/// You can also add an abbreviation by using `#let effect-red = effect.with(text.with(fill: red))` for your own effects.
+/// 
+/// - visible-subslides (int, array, string): `visible-subslides` is a single integer, an array of integers,
+///    or a string that specifies the visible subslides
+///
+///    Read [polylux book](https://polylux.dev/book/dynamic/complex.html)
+///
+///    The simplest extension is to use an array, such as `(1, 2, 4)` indicating that
+///    slides 1, 2, and 4 are visible. This is equivalent to the string `"1, 2, 4"`.
+///
+///    You can also use more convenient and complex strings to specify visible slides.
+///
+///    For example, "-2, 4, 6-8, 10-" means slides 1, 2, 4, 6, 7, 8, 10, and slides after 10 are visible.
+/// 
+/// - fn (function): The function that will be called in the subslide.
+///      Or you can use a method function like `(self: none) => { .. }`.
+///
+/// - cont (content): The content to display when the content is visible in the subslide.
+///
+/// - is-method (boolean): A boolean indicating whether the function is a method function. Default is `false`. 
+#let effect(self: none, fn, visible-subslides, cont) = {
+  if check-visible(self.subslide, visible-subslides) {
+    fn(cont)
+  } else {
+    cont
+  }
+}
+
 /// Uncover content in some subslides. Reserved space when hidden (like `#hide()`).
 ///
 /// Example: `uncover("2-")[abc]` will display `[abc]` if the current slide is 2 or later