String Functions
WCL’s string functions operate on string values and return strings, booleans, lists, or integers depending on the operation. All are pure and side-effect free.
Reference
| Function | Signature | Description |
|---|---|---|
upper | upper(s: string) -> string | Convert to uppercase |
lower | lower(s: string) -> string | Convert to lowercase |
trim | trim(s: string) -> string | Remove leading and trailing whitespace |
trim_prefix | trim_prefix(s: string, prefix: string) -> string | Remove prefix if present |
trim_suffix | trim_suffix(s: string, suffix: string) -> string | Remove suffix if present |
replace | replace(s: string, from: string, to: string) -> string | Replace all occurrences of from with to |
split | split(s: string, sep: string) -> list | Split on separator, returning a list of strings |
join | join(list: list, sep: string) -> string | Join a list of strings with a separator |
starts_with | starts_with(s: string, prefix: string) -> bool | True if s starts with prefix |
ends_with | ends_with(s: string, suffix: string) -> bool | True if s ends with suffix |
contains | contains(s: string, sub: string) -> bool | True if s contains sub |
length | length(s: string) -> int | Number of characters (Unicode code points) |
substr | substr(s: string, start: int, end: int) -> string | Substring from start (inclusive) to end (exclusive) |
format | format(template: string, ...args) -> string | Format string with {} placeholders |
regex_match | regex_match(s: string, pattern: string) -> bool | True if s matches the regex pattern |
regex_capture | regex_capture(s: string, pattern: string) -> list | List of capture groups from the first match |
Examples
upper / lower
let name = "Hello World"
let up = upper(name) // "HELLO WORLD"
let lo = lower(name) // "hello world"
trim / trim_prefix / trim_suffix
let padded = " hello "
let clean = trim(padded) // "hello"
let path = trim_prefix("/api/v1/users", "/api") // "/v1/users"
let file = trim_suffix("report.csv", ".csv") // "report"
replace
let msg = replace("foo bar foo", "foo", "baz") // "baz bar baz"
split / join
let parts = split("a,b,c", ",") // ["a", "b", "c"]
let rejoined = join(parts, " | ") // "a | b | c"
starts_with / ends_with / contains
let url = "https://example.com/api"
let secure = starts_with(url, "https") // true
let is_api = ends_with(url, "/api") // true
let has_ex = contains(url, "example") // true
length / substr
let s = "abcdef"
let n = length(s) // 6
let sub = substr(s, 1, 4) // "bcd"
format
let msg = format("Hello, {}! You have {} messages.", "Alice", 3)
// "Hello, Alice! You have 3 messages."
Placeholders are filled left to right. Each {} consumes one argument.
regex_match
let valid = regex_match("user@example.com", "^[\\w.]+@[\\w.]+\\.[a-z]{2,}$")
// true
regex_capture
let groups = regex_capture("2024-03-15", "(\\d{4})-(\\d{2})-(\\d{2})")
// ["2024", "03", "15"]
Returns an empty list if there is no match. The list contains only the capture groups, not the full match.
String Interpolation
In addition to these functions, WCL supports ${} interpolation inside string literals and block IDs:
let env = "prod"
let tag = "deploy-${env}" // "deploy-prod"
Interpolation converts any value to its string representation automatically.