Strings

String

Strings in Seen are UTF-8 encoded, represented as {len: Int, data: ptr}.

String Interpolation

let name = "World"
println("Hello, {name}!")
println("2 + 2 = {2 + 2}")

Operators

let greeting = "Hello, " + "World!"     // concatenation
let equal = "abc" == "abc"              // equality
let notEqual = "abc" != "xyz"           // inequality

Length

let s = "hello"
let len = s.length()           // byte length: 5

Character Access

let ch = seen_char_at(s, 0)   // Unicode code point at index
let byte = seen_byte_at(s, 0) // raw byte at index

String Functions

Function	Signature	Description
split	(text: String, delimiter: String) r: Array<String>	Split by delimiter
trim	(text: String) r: String	Remove leading/trailing whitespace
startsWith	(text: String, prefix: String) r: Bool	Check prefix
endsWith	(text: String, suffix: String) r: Bool	Check suffix
contains	(text: String, needle: String) r: Bool	Check substring
indexOf	(text: String, needle: String, start: Int) r: Int	Find first occurrence (-1 if not found)

Runtime String Functions

Function	Signature	Description
seen_str_concat_ss	(a: String, b: String) r: String	Concatenate
seen_str_eq_ss	(a: String, b: String) r: Bool	Equality
seen_substring	(s: String, start: Int, end: Int) r: String	Substring extraction
seen_int_to_string	(n: Int) r: String	Int to string
seen_float_to_string	(f: Float) r: String	Float to string
seen_char_to_str	(c: Int) r: String	Char code point to string

Stdlib String Functions

Function	Signature	Description
String_toUpperCase	(s: String) r: String	Uppercase conversion
String_toLowerCase	(s: String) r: String	Lowercase conversion
String_toInt	(s: String) r: Int	Parse as integer
String_toFloat	(s: String) r: Float	Parse as float
String_reverse	(s: String) r: String	Reverse string
String_isEmpty	(s: String) r: Int	Check if empty
String_count	(s: String, needle: String) r: Int	Count occurrences
String_replace	(s: String, old: String, new: String) r: String	Replace all occurrences
String_fromCharCode	(code: Int) r: String	Create from Unicode code point

Extended String Functions (seen_std/src/str/)

Function	Signature	Description
trimStart	(s: String) r: String	Trim leading whitespace
trimEnd	(s: String) r: String	Trim trailing whitespace
lastIndexOf	(s: String, needle: String) r: Int	Last occurrence
lines	(s: String) r: Array<String>	Split into lines
splitWhitespace	(s: String) r: Array<String>	Split on whitespace
words	(s: String) r: Array<String>	Split into words
replaceFirst	(s: String, old: String, new: String) r: String	Replace first occurrence
removePrefix	(s: String, prefix: String) r: String	Remove prefix if present
removeSuffix	(s: String, suffix: String) r: String	Remove suffix if present
ensurePrefix	(s: String, prefix: String) r: String	Add prefix if missing
ensureSuffix	(s: String, suffix: String) r: String	Add suffix if missing
padStart	(s: String, len: Int, ch: Char) r: String	Pad start
padEnd	(s: String, len: Int, ch: Char) r: String	Pad end
repeat	(s: String, n: Int) r: String	Repeat N times
join	(arr: Array<String>, sep: String) r: String	Join with separator

StringBuilder

Efficient string building with amortized allocation:

import str.string

Constructor

let sb = StringBuilder.new()

Methods

Method	Return	Description
append(text: String)	Void	Append string
appendChar(ch: Char)	Void	Append character
appendLine(text: String)	Void	Append string + newline
appendAll(values: Array<String>)	Void	Append all strings
clear()	Void	Clear contents
isEmpty()	Bool	Check if empty
length()	Int	Get total length
toString()	String	Build final string
buildAndClear()	String	Build string and clear builder

Example

let sb = StringBuilder.new()
sb.append("Hello")
sb.append(", ")
sb.append("World!")
let result = sb.toString()  // "Hello, World!"

Character Functions

Function	Signature	Description
Char_isDigit	(c: Int) r: Int	Is digit [0-9]
Char_isAlpha	(c: Int) r: Int	Is alphabetic [A-Za-z]
Char_isAlphanumeric	(c: Int) r: Int	Is alphanumeric
Char_isUpperCase	(c: Int) r: Int	Is uppercase
Char_isLowerCase	(c: Int) r: Int	Is lowercase
Char_isWhitespace	(c: Int) r: Int	Is whitespace
Char_toUpperCase	(c: Int) r: Int	To uppercase
Char_toLowerCase	(c: Int) r: Int	To lowercase
Char_toInt	(c: Int) r: Int	Character to integer (identity)