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make-character-list
string
string-append
string-downcase
string-equal
string-upcase
string<
string<=
string>
string>=
stringp
Version: 4.1
2.4.3 Strings

Some string functions can be found in the section on Sequences as well.

(make-character-list x)  character-listp

  x : t

This function will coerce a value to a list of characters.

Examples:

  > (make-character-list "hello")

  ()

(string x)  t

  x : (or (stringp x) (symbolp x) (characterp x))

Uses coerce to convert the input into a string.

Examples:

  > (string "abc")

  "abc"

  > (string 'abc)

  "ABC"

  > (string #\a)

  "a"

  > (string 123)

  ()

(string-append x y)  t

  x : (stringp x)

  y : (stringp y)

Concatenates two strings together.

Examples:

  > (string-append "ab" "cd")

  "abcd"

  > (string-append 'ab "cd")

  /Users/cce/plt/research/dracula/release/src/language/primiti

  ve-procedures/acl2-prims-scheme.scm:38:28: Dracula program

  broke the contract (case-> (-> (symbols ’string

  ’list) any) (->* ((symbols ’string ’list)) (or/c

   (listof string?) (listof (listof any/c)))

  any)) on here; expected <(or/c (listof string?) (listof

  (listof any/c)))>, given: (ab "cd")

  > (string-append 5 "ab")

  /Users/cce/plt/research/dracula/release/src/language/primiti

  ve-procedures/acl2-prims-scheme.scm:38:28: Dracula program

  broke the contract (case-> (-> (symbols ’string

  ’list) any) (->* ((symbols ’string ’list)) (or/c

   (listof string?) (listof (listof any/c)))

  any)) on here; expected <(or/c (listof string?) (listof

  (listof any/c)))>, given: (5 "ab")

(string-downcase str)  t

  str : (and (stringp str) (standard-char-listp (coerce str 'list)))

Converts the characters in str to lowercase.

Examples:

  > (string-downcase "ABCdef")

  "abcdef"

  > (string-downcase 'ABCdef)

  string-downcase: expects argument of type <string>; given

  ABCdef

  > (string-downcase 12345)

  string-downcase: expects argument of type <string>; given

  12345

(string-equal x y)  t

  x : (and (stringp x) (standard-char-listp (coerce x 'list)))

  y : (and (stringp y) (standard-char-listp (coerce y 'list)))

Compares two strings to see if they are equal.

Examples:

  > (string-equal "ab" "cd")

  ()

  > (string-equal "ab" "ab")

  t

(string-upcase str)  t

  str : (and (stringp str) (standard-char-listp (coerce str 'list)))

Converts the characters in str to uppercase.

Examples:

  > (string-upcase "ABCdef")

  "ABCDEF"

  > (string-upcase 'ABCdef)

  string-upcase: expects argument of type <string>; given

  ABCdef

  > (string-upcase 12345)

  string-upcase: expects argument of type <string>; given

  12345

(string< x y)  t

  x : (stringp x)

  y : (stringp y)

Compares the two strings for lexicographical ordering. Returns non-nil if and only if x precedes y lexicographically. When non-nil, the number returned is the first position at which the strings differ.

Examples:

  > (string< "ab" "cd")

  0

  > (string< "ab" "abc")

  2

  > (string< 'symbol "string")

  /Users/cce/plt/research/dracula/release/src/language/checkin

  g-proc.scm:36:21: Dracula program broke the contract (->

  string? string? any) on here; expected <string?>, given:

  symbol

(string<= x y)  t

  x : (stringp x)

  y : (stringp y)

Compares the two strings for lexicographical ordering. Returns non-nil if and only if x precedes y lexicographically. If they differ, the number returned is the first position at which the strings differ. Otherwise, the number returned is their common length.

Examples:

  > (string<= "ab" "cd")

  0

  > (string<= "ab" "ab")

  2

  > (string<= 'symbol "string")

  /Users/cce/plt/research/dracula/release/src/language/checkin

  g-proc.scm:36:21: Dracula program broke the contract (->

  string? string? any) on here; expected <string?>, given:

  symbol

(string> x y)  t

  x : (stringp x)

  y : (stringp y)

Compares the two strings for lexicographical ordering. Returns non-nil if and only if y precedes x lexicographically. When non-nil, the number returned is the first position at which the strings differ.

Examples:

  > (string> "ab" "cd")

  ()

  > (string> "ab" "ab")

  ()

  > (string> "ba" "ab")

  0

  > (string> 'symbol "string")

  /Users/cce/plt/research/dracula/release/src/language/checkin

  g-proc.scm:36:21: Dracula program broke the contract (->

  string? string? any) on here; expected <string?>, given:

  symbol

(string>= x y)  t

  x : (stringp x)

  y : (stringp y)

Compares the two strings for lexicographical ordering. Returns non-nil if and only if y precedes x lexicographically. If they differ, the number returned is the first position at which the strings differ. Otherwise, the number returned is their common length.

Examples:

  > (string>= "ab" "cd")

  ()

  > (string>= "ab" "ab")

  2

  > (string>= "ba" "ab")

  0

  > (string>= 'symbol "string")

  /Users/cce/plt/research/dracula/release/src/language/checkin

  g-proc.scm:36:21: Dracula program broke the contract (->

  string? string? any) on here; expected <string?>, given:

  symbol

(stringp x)  t

  x : t

Determines whether x is a string.

Examples:

  > (stringp "abcd")

  t

  > (stringp nil)

  ()