String Operations

Weir provides built-in string operations for construction, inspection, and transformation.

Creating Strings

String Literals

"hello, world"
"line one\nline two"
""   ;; empty string

Concatenation with str

str is variadic — it concatenates any number of values into a string, converting each via its Show representation:

(str "Hello, " name "!")              ;; => "Hello, Alice!"
(str "x=" x " y=" y)                  ;; => "x=5 y=10"
(str "score: " (+ base bonus))        ;; => "score: 42"

Inspection

string-length

Returns the length of a string:

(string-length "hello")       ;; => 5
(string-length "")             ;; => 0
(string-length "emoji: hi")   ;; => 9

string-ref

Returns the character code (integer) at a given index:

(string-ref "hello" 0)        ;; => 104 (ASCII 'h')
(string-ref "ABC" 1)          ;; => 66 (ASCII 'B')

string-contains

Checks if a string contains a substring:

(string-contains "hello world" "world")  ;; => true
(string-contains "hello world" "xyz")    ;; => false
(string-contains "hello" "")             ;; => true

len

The generic len function also works on strings:

(len "hello")                  ;; => 5

Extraction

substring

Extracts a substring from start index (inclusive) to end index (exclusive):

(substring "hello world" 0 5)    ;; => "hello"
(substring "hello world" 6 11)   ;; => "world"
(substring "abcdef" 2 4)         ;; => "cd"

Transformation

string-upcase

Converts all characters to uppercase:

(string-upcase "hello")           ;; => "HELLO"
(string-upcase "Hello World")     ;; => "HELLO WORLD"

string-downcase

Converts all characters to lowercase:

(string-downcase "HELLO")         ;; => "hello"
(string-downcase "Hello World")   ;; => "hello world"

string-trim

Removes leading and trailing whitespace:

(string-trim "  hello  ")         ;; => "hello"
(string-trim "\n  spaced  \t")    ;; => "spaced"

Conversion

char-to-string

Converts a character code (integer) to a single-character string:

(char-to-string 65)               ;; => "A"
(char-to-string 104)              ;; => "h"
(char-to-string 10)               ;; => "\n"

Summary

Function	Signature	Description
str	(Fn ['a ...] String)	Concatenate values into a string
string-length	(Fn [String] i64)	Length of string
substring	(Fn [String i64 i64] String)	Extract substring (start, end)
string-ref	(Fn [String i64] i64)	Character code at index
string-contains	(Fn [String String] Bool)	Substring search
string-upcase	(Fn [String] String)	To uppercase
string-downcase	(Fn [String] String)	To lowercase
string-trim	(Fn [String] String)	Trim whitespace
char-to-string	(Fn [i64] String)	Char code to string