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base-string

base-string Type

Supertypes:

base-string, string, vector, array, sequence, t

Description:

The type base-string is equivalent to (vector base-char). The base string representation is the most efficient string representation that can hold an arbitrary sequence of standard characters.

Compound Type Specifier Kind:

Abbreviating.

Compound Type Specifier Syntax:

(base-string [size])

Compound Type Specifier Arguments:

size—a non-negative fixnum, or the symbol *.

Compound Type Specifier Description:

This is equivalent to the type (vector base-char size); that is, the set of base strings of size size.

Expanded Reference: base-string​

base-string is equivalent to (vector base-char)​

A base-string is a string whose elements are of type base-char. It is the most efficient string representation for standard characters.

;; In SBCL, string literals have element-type CHARACTER, not BASE-CHAR
(typep "hello" 'base-string)
=> NIL

(subtypep 'base-string 'string)
=> T
=> T

Type checking with the compound type specifier​

The compound form (base-string size) specifies a base-string of a particular length.

;; In SBCL, string literals are not base-strings
(typep "abc" '(base-string 3))
=> NIL

(typep "abc" '(base-string 5))
=> NIL

(typep "abc" '(base-string *))
=> NIL

Relationship to other string types​

base-string is a subtype of string and a supertype of simple-base-string.

(subtypep 'base-string 'string)
=> T
=> T

(subtypep 'simple-base-string 'base-string)
=> T
=> T

(subtypep 'base-string 'vector)
=> T
=> T

Creating base-strings with make-string​

make-string with :element-type 'base-char creates a simple base-string.

(let ((s (make-string 4 :initial-element #\Z :element-type 'base-char)))
  (list s (typep s 'base-string)))
=> ("ZZZZ" T)