Add use_effect hook

Cargo.toml

@@ -1,4 +1,5 @@
 [workspace]
+resolver = "2"
 members = [
     "crates/concoct",
     "crates/concoct-web",

crates/concoct/Cargo.toml

@@ -11,6 +11,7 @@ full = []
 
 [dependencies]
 futures = "0.3.30"
+rustc-hash = "1.1.0"
 slotmap = "1.0.7"
 tracing = "0.1.40"
 

crates/concoct/src/hook/mod.rs

@@ -1,6 +1,9 @@
 mod use_context;
 pub use use_context::{use_context, use_provider};
 
+mod use_effect;
+pub use self::use_effect::use_effect;
+
 mod use_ref;
 pub use use_ref::use_ref;
 

crates/concoct/src/hook/use_effect.rs

@@ -0,0 +1,20 @@
+use super::use_ref;
+use rustc_hash::FxHasher;
+
+use std::hash::{Hash, Hasher};
+
+pub fn use_effect(dependencies: impl Hash, effect: impl FnOnce()) {
+    let mut hasher = FxHasher::default();
+    dependencies.hash(&mut hasher);
+    let hash = hasher.finish();
+
+    let mut is_initial = false;
+    let last_hash = use_ref(|| {
+        is_initial = true;
+        hash
+    });
+
+    if is_initial || hash != *last_hash {
+        effect()
+    }
+}