chickadee » srfi-130 » string-join


This procedure is a simple unparser--it pastes strings together using the delimiter string.

The grammar argument is a symbol that determines how the delimiter is used, and defaults to infix.

  • infix means an infix or separator grammar: insert the delimiter between list elements. An empty list will produce an empty string--note, however, that parsing an empty string with an infix or separator grammar is ambiguous. Is it an empty list, or a list of one element, the empty string?
  • strict-infix means the same as infix, but will signal an error if given an empty list.
  • suffix means a suffix or terminator grammar: insert the delimiter after every list element. This grammar has no ambiguities.
  • prefix means a prefix grammar: insert the delimiter before every list element. This grammar has no ambiguities.

The delimiter is the string used to delimit elements; it defaults to a single space " ".


(string-join '("foo" "bar" "baz") ":")         => "foo:bar:baz"
(string-join '("foo" "bar" "baz") ":" 'suffix) => "foo:bar:baz:"

;; Infix grammar is ambiguous wrt empty list vs. empty string,
(string-join '()   ":") => ""
(string-join '("") ":") => ""

;; but suffix & prefix grammars are not.
(string-join '()   ":" 'suffix) => ""
(string-join '("") ":" 'suffix) => ":"