Strings

upper(s) and lower(s) return a new string with the case folded. They handle Unicode, so accented characters and non-Latin scripts round-trip correctly.

<p> [upper('hello')]
<p> [lower('WORLD')]

trim(s) removes whitespace (spaces, tabs, newlines) from both ends of the string. Use it to clean up form input before validation. Inner whitespace is left alone, so reach for regex.replace when you need to collapse runs.

<p> ([trim('  hi  ')])

split(s, sep) cuts a string on a delimiter into an array. join(arr, sep) is the inverse: it turns an array of strings into a delimited string. Together they let you reshape "list-as-string" data without writing a loop.

<p> [split('a,b,c', ',')]
<p> [join(items, ' / ')]

replace(s, from, to) swaps every occurrence of a literal substring. There are no escape rules: every character is matched literally. For pattern-based replacement, use regex.replace from the regex namespace.

<p> [replace('foo bar foo', 'foo', 'baz')]

Each takes the haystack first and the needle second, returning true or false. contains also works on arrays (element membership) and objects (key membership), handy when the data shape changes between two call sites.

<p> [starts_with('hello world', 'hello')]
<p> [ends_with('hello world', 'world')]
<p> [contains('hello world', 'lo wo')]
<p> [contains(items, 'pears')]

pad_left(s, width, char) prepends the pad character until the result is the requested width; pad_right appends instead. If the input is already at or over the width, it's returned unchanged. A common use is zero-padding numeric IDs for sortable filenames.

<p> ([pad_left('7', 3, '0')])
<p> ([pad_right('7', 3, '.')])

repeat(s, n) joins n copies of s into one string. Useful for rules in plain-text output, leader dots, or progress bars.

<p> [repeat('ab', 3)]
<p> [repeat('-', 20)]

format(template, args...) substitutes each {} with the next argument. There are no named or indexed slots: order is the contract. The format spec mirrors the simplest subset of Python f-strings on purpose, so reach for string concatenation when you need anything richer.

<p> [format('hi {}', 'world')]
<p> [format('{} + {} = {}', 1, 2, 3)]