What is so special about Lisp macros?
It allows you do do things like splicing tokens in, with our without the double quotes, etc. But that’s about it. In Lisp, your macro can perform any computation on its arguments whatsoever. It can decide which arguments to evaluate, and whether they should be evaluated zero times, once, or any other number of times.
What are Common Lisp macros?
The Common Lisp macro facility allows the user to define arbitrary functions that convert certain Lisp forms into different forms before evaluating or compiling them. This is done at the expression level, not at the character-string level as in most other languages.
What is a macro Lisp?
A macro is an ordinary piece of Lisp code that operates on another piece of putative Lisp code, translating it into (a version closer to) executable Lisp. That may sound a bit complicated, so let’s give a simple example. Suppose you want a version of setq that sets two variables to the same value.
What makes Lisp unique?
Lisp programs are trees of expressions, each of which returns a value. (In some Lisps expressions can return multiple values.) This is in contrast to Fortran and most succeeding languages, which distinguish between expressions and statements.
Why do I have a lisp?
It is syntax you can learn in three minutes and use to express anything. The biggest advantage, and one that seems to slip past most who just give Lisp a cursory glance, is that code and data are expressed the same way. A Lisp expression is nothing more than a list of symbols.
What are scheme macros?
A macro is a symbol that has a transformer procedure associated with it. When Scheme encounters a macro-expression — i.e., a form whose head is a macro —, it applies the macro’s transformer to the subforms in the macro-expression, and evaluates the result of the transformation.
What is Progn Lisp?
The general purpose special operator progn is used for evaluating zero or more forms. The value of the last form is returned.
What is another word for Lisp?
What is another word for lisp?
| impediment | faltering |
|---|---|
| hesitancy | stammer |
| stutter | speech defect |
| speech impediment | impairment |
| speech disorder | falter |
Is it bad to have a Lisp?
No! It is never too late to work on remediating a sound deviation such as a lisp. Although a lisp is considered a relatively minor speech error, many adults feel that a lisp negatively impacts their professional or social life. This in turn can contribute to a decrease in confidence around social communication.
How are macros implemented?
The trick to implementation a macro system is to tell your compiler to be lazy. Put in another way, when the compiler encounters a function, it first evaluates its formal parameter list, yields the results and passes them to the function.
How do macros work in Lisp?
The basic mechanism of Lisp macros is simple, but has subtle complexities, so learning your way around it takes a bit of practice. A macro is an ordinary piece of Lisp code that operates on another piece of putative Lisp code, translating it into (a version closer to) executable Lisp.
What is defmacro in Lisp?
The mistake is to suppose that once a macro is called, the Lisp system enters a “macro world,” so naturally everything in that world must be defined using defmacro. This is the wrong picture. The right picture is that defmacro enables a step into the ordinary Lisp world, but in which the principal object of manipulation is Lisp code.
Is there a macro in C?
The basic idea has since been used many times, notably in the C preprocessor. The name “macro” is perhaps not ideal, since it connotes nothing relevant to what it names, but we’re stuck with it.) Although many languages have a macro facility, none of them are as powerful as Lisp’s.
What is the difference between macros and lazy pure languages?
In other words, the meaning of an expression in a lazy pure language is a function solely of the meanings of the component expressions; while macros can yield semantically distinct results from semantically equal arguments. In this sense, macros are more powerful, while laziness is correspondingly more well-behaved semantically.