Add NonemptyListof.

scribblings/utils.scrbl

@@ -45,6 +45,12 @@ the variables.
 
 }
 
+@defform[(NonemptyListof a)]{
+
+A @racket[(Listof a)] which contains at least one element.
+
+}
+
 @section{Type utilities}
 
 Typed Racket's @racket[cast] should only be used as a last resort, because it

utils.rkt

@@ -4,7 +4,7 @@
          (for-syntax syntax/parse racket/syntax racket/list))
 
 (provide
- Variable VariableMapping GeneralPair
+ Variable VariableMapping GeneralPair NonemptyListof
 
  assert-type for/first/typed for*/first/typed define/abstract/error
  relax-arg-type/any
@@ -28,6 +28,8 @@
 (define-type Variable Symbol)
 (define-type (VariableMapping A) (Immutable-HashTable Variable A))
 
+(define-type (NonemptyListof a) (Pairof a (Listof a)))
+
 (define-syntax-parse-rule (assert-type e:expr type:expr)
   (assert e (make-predicate type)))