quasiquoted

Quasiquoting is a programming language construct that allows for the convenient construction of code or data structures where some parts are fixed and others are variable. It is particularly useful in languages that support metaprogramming, such as Lisp dialects. A quasiquote, often denoted by a backtick (` `), behaves like a quoted expression, meaning its contents are generally treated as literal data. However, it also provides mechanisms to interpolate or "unquote" specific parts of the expression, allowing them to be evaluated and their results substituted into the quasiquoted structure.

The primary operator used in conjunction with quasiquotation is unquote, typically represented by a comma (,). When an unquote operator precedes an expression within a quasiquoted structure, that expression is evaluated, and its result replaces the unquoted part. This allows for dynamic generation of code or data. For example, a quasiquoted list might contain a fixed prefix and a variable suffix that is computed at runtime.

A related operator is unquote-splicing, often denoted by a comma followed by an at-sign (,@). This operator is used when the result of the unquoted expression is a list or sequence. Instead of inserting the entire list as a single element, unquote-splicing inserts the elements of the list individually into the quasiquoted structure. This is crucial for building lists or other collections dynamically. Quasiquotation, with its unquote and unquote-splicing mechanisms, simplifies the process of generating code that generates other code, or constructing complex data structures based on varying inputs.