make thunks better

Signed-off-by: Xe Iaso <me@christine.website>

thunk.go

@@ -15,17 +15,17 @@ package gonads
 // In this example, `addTwo` is a thunk that contains a partially applied addCurr
 // invocation.
 type Thunk[T any] struct {
-	doer func(T) T // action being thunked
+	doer func() T // action being thunked
 	o    Option[T] // cache for complete thunk data
 }
 
 // Force evaluates a Thunk's action if it needs to, otherwise it returns the
 // previously evaluated result.
-func (t Thunk[T]) Force(inp T) T {
+func (t Thunk[T]) Force() T {
 	if t.o.IsSome() {
 		return t.o.Yank()
 	}
 
-	t.o.Set(t.doer(inp))
+	t.o.Set(t.doer())
 	return t.o.Yank()
 }

thunk_test.go

@@ -20,13 +20,18 @@ func TestThunkFib(t *testing.T) {
 	cache[0].o.Set(0)
 	cache[1].o.Set(1)
 
-	fib := func(n int) int {
-		return cache[n-1].Force(n-1) + cache[n-2].Force(n-2)
+	var fib func(int) int
+	fib = func(n int) int {
+		if cache[n].o.IsSome() {
+			return *cache[n].o.val
+		}
+		return fib(n-1) + fib(n-2)
 	}
 	
 	for i := range cache {
-		cache[i].doer = fib
+		i := i
+		cache[i].doer = func() int { return fib(i) }
 	}
 
-	t.Log(cache[40].Force(40))
+	t.Log(cache[40].Force())
 }