deprecate function.tap

Author: giacomocavalieri

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## Unreleased
+
+- The `tap` function from the `function` module has been deprecated.
+
 ## v0.65.0 - 2025-09-29
 
 - The performance of the `drop_start` function from the `string` module has

src/gleam/function.gleam

@@ -9,6 +9,7 @@ pub fn identity(x: a) -> a {
 ///
 /// Useful for running synchronous side effects in a pipeline.
 ///
+@deprecated("This function has been deprecated. You can bind the value you want to tap to a variable instead.")
 pub fn tap(arg: a, effect: fn(a) -> b) -> a {
   effect(arg)
   arg