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String constants

Strings are enclosed by double quotes ".

Simple Strings

A plain string declared with double quotes such as "some string" can be assigned to fields of type String:

Internally, a plain string is an instance of the standard library feature conststring, which inherits from string. However, its static type is String, so it cannot be assigned to a field of type conststring:

Escaped Characters

A plain string must not contain any of the characters $, {, }, " or \. To include one of these characters, it must be escaped by putting a backslash \ in front of it.

Also, a plain string must not contain any ASCII control characters in the range of 0x00..0x1f nor the DEL character (0x7f). In particular, a new line within a plain string is an error.

To include any of these forbidden characters or certain ASCII control characters, an escape sequence using a backslash \ can be used:

Escape sequence character ASCII code
\"" 0x22
\$$ 0x24
\'' 0x27
\\\ 0x5c
\{{ 0x7b
\}} 0x7d

Here is a small example using escaped control and special characters:

Converting instances to strings

All Fuzion features are heirs of Object, which provides a feature as_string to create an instance of String from any Fuzion instance. Any feature may redefine as_string to create a string representation appropriate for the specific feature.

The operator prefix $ is defined as a synonym for as_string, so a call $v is shorthand for v.as_string:

Embedded Expressions

Strings can be concatenated with the string representation of any instance using infix +:

Single identifiers or numeric literals can be embedded into a string literal using a $ immediately before the identifier as follows.

This embedding using $ does not work for expressions that consist of more than an identifier. For more complex expressions, you can use curly braces { and }:

This works even for code that spans several lines:

Arbitrary nesting of strings and expressions is also possible:

Multi-line Strings

Multiline strings start and end with a fat quotation """. They mostly work just like 'normal' strings but have the following peculiarities.

  • A multiline string is required to start in the first line following the fat quotation.
  • The first line of the multiline string is the reference for the indentation to be used throughout the rest of the string. Thus all lines of the mulitline strings have to indented at least as much as the first line.
  • A multiline string may use interpolation with $ and {} just like 'normal' strings.
  • Arbitrary nesting of multiline strings is allowed.
  • Trailing whitespace in multiline strings is disallowed.
  • For adding whitespace at the beginning of the first line or at the end of lines use escape codes described above.
  • Line terminators in multiline strings are normalized to LF unless CR is explicitly included by using the escape code CR.