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What does colon mean in Lisp?
It’s a reader macro. Colon is used to tell the reader which package to intern symbols in. package::symbol tells the reader to INTERN a symbol called SYMBOL in the package PACKAGE. package:symbol means the symbol must be exported from that package. :symbol is actually short for KEYWORD:SYMBOL.
What is symbol in 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.
What is a hook Emacs?
A hook is a variable where you can store a function or functions to be called on a particular occasion by an existing program. Emacs provides hooks for the sake of customization. Most often, hooks are set up in the init file (see Init File), but Lisp programs can set them also.
What is symbol in Emacs?
A symbol in GNU Emacs Lisp is an object with a name. The symbol name serves as the printed representation of the symbol. In ordinary Lisp use, with one single obarray (see Creating Symbols), a symbol’s name is unique—no two symbols have the same name.
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 is prog mode?
Program mode (the “P” on the mode dial of most DSLRs) means that the camera still sets the exposure for you. It chooses the correct aperture and shutter speed for the light available, so your shot is correctly exposed. Program mode also unlocks other functions that give you more creative control over your images.
How do you add a hook in Emacs?
You can set a hook variable with setq like any other Lisp variable, but the recommended way to add a function to a hook (either normal or abnormal) is to use add-hook , as shown by the following examples. See Hooks in The Emacs Lisp Reference Manual , for details.
What is the word symbol mean?
1 : something that stands for something else : emblem The eagle is a symbol of the United States. 2 : a letter, character, or sign used instead of a word to represent a quantity, position, relationship, direction, or something to be done The sign + is the symbol for addition. symbol. noun.
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.
How are defconst constants defined in Emacs Lisp?
These constants are fundamentally different from the constants defined using the defconst special form (see Defining Variables). A defconst form serves to inform human readers that you do not intend to change the value of a variable, but Emacs does not raise an error if you actually change it.
Why does Emacs keep an interned copy of the empty string?
As a (very minor) space and performance optimization, starting with Emacs 23, Emacs keeps an interned copy of the empty string as a single object While it is quite common in other programming languages to work on strings contained in variable s, in Emacs it is also common to work on text in buffer s.
What’s the equivalent of kill-region in Lisp?
The Lisp equivalent of ‘kill-region’ ( ‘C-w’) but without kill-ring side effects:: According to the ElispManual, “Few programs need to use the ‘region-beginning’ and ‘region-end’ functions.” This is because Lisp code should not rely on nor “alter the mark unless altering the mark is part of the user-level functionality of the command.