String

Strings in Risor are based on the underlying string type in Go. As such, they support unicode and various operations like indexing operate on the underlying runes within the string.

Quote Types

There are three ways to quote strings in Risor source code:

'single quotes: supports interpolated {vars}'
"double quotes: equivalent to Go strings"
`backticks: raw strings that may span multiple lines`

The single quoted string approach offers string formatting via interpolation, much like f-strings (opens in a new tab) in Python. Arbitrary Risor expressions can be embedded within parentheses and resolved during evaluation. In Risor, the restriction on these expressions is that they cannot contain curly braces, since those are used to mark the beginning and end of the template expression.

An example with simple expressions:

>>> name := "jean"
"jean"
>>> age := 30
30
>>> '{name} is {age} years old'
"jean is 30 years old"

Another example:

>>> nums := [0, 1, 2, 3]
[0, 1, 2, 3]
>>> 'the max is {math.max(nums)} and the length is {len(nums)}'
"the max is 3 and the length is 4"

Container Operations

Strings in Risor implement the object.Container interface, which means they support typical container-style operations:

>>> s := "hello"
"hello"
>>> s[0]
"h"
>>> len(s)
5
>>> s[1:3]
"el"
>>> s[1:]
"ello"
>>> s[:1]
"h"
>>> iter(s)
string_iter("hello")
>>> iter(s).next()
iter_entry(0, "h")

Related Built-ins

chr(int)

Converts an Int to the corresponding unicode rune, which is returned as a String. The ord built-in performs the inverse transformation.

ord(string)

Converts a unicode character to the corresponding Int value. The chr built-in performs the inverse transformation. An error is generated if a multi-rune string is provided.

sprintf(string, ...any)

Wraps fmt.Sprintf to format the string with the provided arguments. Risor objects are converted to their corresponding Go types before being passed to fmt.Sprintf.

string(x)

Returns the string representation of any Risor object.

Methods

string.contains(s)

Returns a bool that indicates if s is a substring of this string.

string.has_prefix(s)

Checks whether the string begins with the prefix s.

string.has_suffix(s)

Checks whether the string ends with the suffix s.

string.count(s)

Returns the number of occurrences of s in this string.

string.join(list)

Return the joined result of the given list of strings, using this string as the separator.

string.split(separator)

Splits this string on all occurrences of the given separator, returning the resulting list of strings.

string.fields()

Splits this string on whitespace, returning the list of non-whitespace substrings. If this string is only whitespace, an empty list is returned.

string.index(s)

Returns the index of the first occurence of s in this string, or -1 if s is not present.

string.last_index(s)

Returns the index of the last occurence of s in this string, or -1 if s is not present.

string.replace_all(old, new)

Returns a copy of this string with all occurrences of old replaced by new.

string.to_lower()

Returns a copy of this string that is transformed to all lowercase.

string.to_upper()

Returns a copy of this string that is transformed to all uppercase.

string.trim(cutset)

Returns a copy of this string with all leading and trailing characters contained in cutset removed.

string.trim_prefix(prefix)

Returns a copy of this string without the given prefix. This is a no-op if this string doesn't start with prefix.

string.trim_space()

Returns a copy of this string without the leading and trailing whitespace.

string.trim_suffix(suffix)

Returns a copy of this string without the given suffix. This is a no-op if this string doesn't end with suffix.