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What are Lisp symbols?
A Lisp symbol is a data object that has three user-visible components:
- The property list is a list that effectively provides each symbol with many modifiable named components.
- The print name must be a string, which is the sequence of characters used to identify the symbol.
What is a symbol in Common Lisp?
In LISP, a symbol is a name that represents data objects and interestingly it is also a data object. What makes symbols special is that they have a component called the property list, or plist.
Do you need to know Lisp to use Emacs?
No, it’s not strictly necessary. You will probably write elisp, but mostly just set variables and insert the necessary snippets for any mode or package you want to use ( setq , require etc). Most of that is done by copying and pasting, so no real knowledge of elisp is required.
What are the three functions required by LISP?
Lisp: Basic functions. DEFUN is used to define new functions. It takes three parameters, which are implicitly quoted (see below): (1) the name of the function, as an atom; (2) the formal parameter list of the function, as a list of atoms; and (3) an S-expression representing the body of the function.
What does LISP mean?
1 : to pronounce the sibilants \s\ and \z\ imperfectly especially by turning them into \th\ and \t͟h\ 2 : to speak falteringly, childishly, or with a lisp. transitive verb. : to utter falteringly or with a lisp.
What are the special symbols and its function?
A special character is one that is not considered a number or letter. Symbols, accent marks, and punctuation marks are considered special characters. Similarly, ASCII control characters and formatting characters like paragraph marks are also special characters.
What is Setf Lisp?
setf is actually a macro that examines an access form and produces a call to the corresponding update function. Given the existence of setf in Common Lisp, it is not necessary to have setq, rplaca, and set; they are redundant. They are retained in Common Lisp because of their historical importance in Lisp.
What are basic functions of LISP?
How does an obarray work in Emacs Lisp?
In Emacs Lisp, an obarray is actually a vector. Each element of the vector is a bucket; its value is either an interned symbol whose name hashes to that bucket, or 0 if the bucket is empty. Each interned symbol has an internal link (invisible to the user) to the next symbol in the bucket.
When to use keyword symbols in Emacs Lisp?
A symbol whose name starts with a colon (‘:’) is called a keyword symbol. These symbols automatically act as constants, and are normally used only by comparing an unknown symbol with a few specific alternatives.
Why do you need uninterned symbols in Emacs?
Creating an uninterned symbol is useful in generating Lisp code, because an uninterned symbol used as a variable in the code you generate cannot clash with any variables used in other Lisp programs. In Emacs Lisp, an obarray is actually a vector.
What to do with a symbol in Lisp?
When value cell is not void, the symbol is considered as a variable. Store function definition object, lisp macros, or other objects that can act as function. Hold a list of name/value pairs. Used for storing meta info about the symbol, such as function state, font face spec (for syntax coloring), deprecation flag, etc.