utils: Type drop-first-last.

scribblings/utils.scrbl

@@ -226,6 +226,16 @@ Reads a list of symbols from a string.
 (read-symbol-list "a b c")
 ]}
 
+@defproc[(drop-first-last (str String)) String]{
+
+Removes the first and the last symbol of a given string.
+
+Useful for removing the parentheses in string representations of lists.
+
+@examples[#:eval utils-evaluator
+(drop-first-last "(a b)")
+]}
+
 @section{Additional graph utilities}
 @defproc[(dotit [graph Graph]) Void]{
 

utils.rkt

@@ -20,7 +20,8 @@
    eval-with eval1-with auto-hash-ref/explicit auto-hash-ref/:
    extract-symbols any->string stringify-variable-mapping string->any
    handle-org-booleans map-sexp read-org-sexp unorg unstringify-pairs
-   read-org-variable-mapping unorgv read-symbol-list dotit)
+   read-org-variable-mapping unorgv read-symbol-list drop-first-last
+   dotit)
 
   (define-type Variable Symbol)
   (define-type (VariableMapping A) (Immutable-HashTable Variable A))
@@ -258,6 +259,14 @@
     (test-case "read-symbol-list"
       (check-equal? (read-symbol-list "a b c") '(a b c))))
 
+  (: drop-first-last (-> String String))
+  (define (drop-first-last str)
+    (substring str 1 (- (string-length str) 1)))
+
+  (module+ test
+    (test-case "drop-first-last"
+      (check-equal? (drop-first-last "(a b)") "a b")))
+
   (define dotit (compose display graphviz))
   )
 
@@ -265,14 +274,14 @@
 (provide eval-with eval1-with auto-hash-ref/explicit auto-hash-ref/:
          extract-symbols any->string stringify-variable-mapping string->any
          map-sexp read-org-sexp unorg unstringify-pairs
-         read-org-variable-mapping unorgv read-symbol-list dotit)
+         read-org-variable-mapping unorgv read-symbol-list drop-first-last
+         dotit)
 
 ;;; Untyped section.
 
 (provide
  ;; Functions
- (contract-out [drop-first-last (-> string? string?)]
-               [list-sets->list-strings (-> (listof (set/c any/c)) (listof string?))]
+ (contract-out [list-sets->list-strings (-> (listof (set/c any/c)) (listof string?))]
                [pretty-print-set-sets (-> (set/c (set/c symbol?) #:kind 'dont-care) string?)]
                [update-vertices/unweighted (-> graph? (-> any/c any/c) graph?)]
                [update-graph (->* (graph?)
@@ -317,17 +326,6 @@
   (or/c (list/c key-contract val-contract)
         (cons/c key-contract val-contract)))
 
-;;; Removes the first and the last symbol of a given string.
-;;;
-;;; Useful for removing the parentheses in string representations of
-;;; lists.
-(define (drop-first-last str)
-  (substring str 1 (- (string-length str) 1)))
-
-(module+ test
-  (test-case "drop-first-last"
-    (check-equal? (drop-first-last "(a b)") "a b")))
-
 ;;; Converts a list of sets of symbols to a list of strings containing
 ;;; those symbols.
 (define (list-sets->list-strings lst)