improved performance

day01-hard/main.scm

@@ -59,7 +59,7 @@
   '(1 2 3)
   ((first is-not-empty) '(() (1 2 3))))
 
-(define (coalesce-not-empty default) (lambda (value) ((first is-not-empty) (list value default))))
+(define (coalesce-not-empty default-lazy) (lambda (value) (if (null? value) (default-lazy) value)))
 
 (define (truthy-chaining f) (lambda (value) (if value (f value) #f)))
 
@@ -116,7 +116,7 @@
       (null? values)
       '(())
       ((compose (list
-        (coalesce-not-empty (f (cdr values)))
+        (coalesce-not-empty (lambda () (f (cdr values))))
         flat
         (filter id)
         (map