diff --git a/TODO.md b/TODO.md
index dc51c32..058a5b4 100644
--- a/TODO.md
+++ b/TODO.md
@@ -1,4 +1,4 @@
-用 generic 函数定义 lift -- 删除 `skipIncompleteInputs`
+删除 `skipIncompleteInputs`
 monads/supported-monad -- 删除 `maybeUnwrapSupported`
 
 > propagator 支持 dependencies for provenance
diff --git a/src/monad/index.ts b/src/monad/index.ts
index 52927c5..cf90839 100644
--- a/src/monad/index.ts
+++ b/src/monad/index.ts
@@ -1,5 +1,27 @@
 import { defineGeneric } from "../generic/index.js"
 
-export const fmap = defineGeneric({ default: (f, mx) => f(mx) })
-export const join = defineGeneric({ default: (mmx) => mmx })
-export const bind = (mx: any, f: (x: any) => any) => join(fmap(f, mx))
+// (f: (A) -> B, ma: M(A)) -> M(B)
+export const fmap = defineGeneric({ default: (f, ma) => f(ma) })
+
+// (mma: M(M(A))) -> M(A)
+export const join = defineGeneric({ default: (mma) => mma })
+
+// (ma: M(A), f: (A) -> M(B)) -> M(B)
+export const bind = (ma: any, f: (x: any) => any) => join(fmap(f, ma))
+
+// (f: (A0, A1, ...) -> B) -> (M(A0), M(A1), ...) -> M(B)
+export function naryFmap(
+  f: (...args: Array<any>) => any,
+): (...margs: Array<any>) => any {
+  return (...margs) => {
+    function loop(margs: Array<any>, f: (...args: Array<any>) => any): any {
+      if (margs.length === 0) return f()
+
+      return bind(margs[0], (arg) =>
+        loop(margs.slice(1), (...restArgs) => f(arg, ...restArgs)),
+      )
+    }
+
+    return loop(margs, f)
+  }
+}
diff --git a/src/monads/nothing-monad.ts b/src/monads/nothing-monad.ts
index 42415fd..227ba7c 100644
--- a/src/monads/nothing-monad.ts
+++ b/src/monads/nothing-monad.ts
@@ -3,5 +3,5 @@ import { defineHandler } from "../generic/index.js"
 import { fmap, join } from "../monad/index.js"
 import { isFunction } from "../utils/isFunction.js"
 
-defineHandler(fmap, [isFunction, isNothing], (f, mx) => nothing)
-defineHandler(join, [isNothing], (mmx) => nothing)
+defineHandler(fmap, [isFunction, isNothing], (f, ma) => nothing)
+defineHandler(join, [isNothing], (mma) => nothing)
diff --git a/src/propagator/definePrimitive.ts b/src/propagator/definePrimitive.ts
index 0035ba6..01a2939 100644
--- a/src/propagator/definePrimitive.ts
+++ b/src/propagator/definePrimitive.ts
@@ -1,5 +1,7 @@
 import { Cell, addPropagator, isNothing, nothing, put } from "../cell/index.js"
 import { isSupported } from "../dependency/index.js"
+import { naryFmap } from "../monad/index.js"
+import "../monads/nothing-monad.js"
 import { schedule } from "../scheduler/index.js"
 import type { MaybePromise } from "../utils/MaybePromise.js"
 import { repeatApply } from "../utils/repeatApply.js"
@@ -87,8 +89,7 @@ function watch(cells: Array<Cell<any>>, propagator: Propagator): void {
 function lift(
   fn: (...args: Array<any>) => MaybePromise<any>,
 ): (...args: Array<Cell<any>>) => MaybePromise<any> {
-  fn = maybeUnwrapSupported(fn)
-  fn = skipIncompleteInputs(fn)
+  fn = naryFmap(fn)
 
   return (...inputs) => fn(...inputs.map((input) => input.content))
 }