the binding concept on LISP programming language
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what is lisp used for
scheme programming language
lisp full form
what is the concept of biding on LISP program language ?
are dynamic or static ?? or no one of them ?
Can anyone support in this regard.
Static binding, which is the norm in most languages, means that the value of a variable is determined solely by the part (function, procedure, block, whatever) of the program in which the variable is declared, and the variable is not accessible outside that part. Dynamic binding means that the value of a variable depends on the whole history of the program's execution, and the variable is accessible anywhere in the program, but the value can be set on entry to a part of the program and everything it calls and restored on exit from that part.
Historically Lisps had dynamic binding in the interpreter and both static and dynamic binding in the compiler, with declarations to work around this. Scheme and Common Lisp removed this discrepancy, making static binding the default but still preserving dynamic binding. Perl also started with just dynamic binding using
let, but now also has static binding with
my. Only a few Lisps now make dynamic binding the default or only choice, notably Elisp, Picolisp, and newLisp. However, Picolisp does provide closures that provide lexical binding, and newLisp works around the problems of dynamic binding with extensive use of namespaces (in principle, if every function has its own namespace for variables, dynamic and static binding are equivalent).
What is LISP (list processing)?, Information Processing Language was the first AI language, from 1955 or 1956, and already included many of the concepts, such as list-processing and recursion, At the vary basic, binding is assigning one thing to another, usually, values to variables either by explicit declaration or implicit declaration. For the newbies in programming, the terms, explicit and implicit declaration seems daunting its really not. Explicit declaration simply implies a statement that defines the variable name and it's type e.g
LISP as in Common Lisp has both both. All global variables are dynamically bound, or special in CL lingo.
(defparameter *par* 5) (defvar *var* 10) (defun test () (+ *par* *var*)) (test) ; ==> 15 (let ((*par* 9) (*var* 21)) (test)) ; ==> 30
Now if the variables would have been static you should have had the same result from both calls to
test, but it isn't.
If you by coincident named a local binding with the same name as a global you could get strange results from other calls that use these and they would be very difficult to spot. To not confuse global variables with lexical ones there is a naming convention using
*earmuffs* which is perhaps the most important convention in CL.
Every thing else is static (or lexical).
There are other types of LISP though. Eg. Scheme has only static binding. Thus the example above converted to Scheme would yield
15 each time. A special thing about static bindings are closures:
(define (get-proc proc initial-arg) (lambda args (apply proc initial-arg args))) (define add10 (get-proc + 10)) ; the + and 10 are bound in the result (define div10 (get-proc / 10)) ; the - and 10 are bound in the result (add10 2) ; ==> 12 (div10 2) ; ==> 5
PicoLisp has only dynamic binding and thus closures doesn't exist in and thus
initial-arg wouldn't be defined by the time we call the generated procedures if you tried the same as the Scheme example. It does work in CL as long as you don't mix static and dynamic variable names.
Comparing LISP and Object-Oriented Programming Languages, Common Lisp (CL) is a dialect of the Lisp programming language, published in ANSI standard The macro defun defines functions where a function definition gives the name of the In Common Lisp, a special variable which has only a top-level binding behaves just like a global variable in other programming languages. Programming Language Concepts/Binding and Scope Static vs Dynamic Scope/Binding Dynamic binding Dynamic binding Functions called update their declarations on the environment at run-time. Delete them on return. Current stack of activated blocks is signiﬁcant in binding. Lisp and some script languages apply dynamic binding. 1 int x=1,y=2; 2 int
In Lisp "variables" are described as name->value associations called "bindings"; a collection of bindings is named "environment".
When for example you have a function
(defun square (x) (* x x))
and you call the function with
on function enter a new "environment" will be established, containing the "binding"
x -> 12.
In C++-like languages these concepts are normally called "stack frames" (environments) and "local variables" (bindings). Note however than a "stack frame" idea cannot describe correctly what happens in Lisp for example during capture:
(defun kmul (k) ;; returns a function that multiplies by k its argument (lambda (x) (* x k))) (let ((k12 (kmul 12))) (print (funcall k12 3))) ; --> 36
kmul on enter will have an environment containing the binding
k -> 12 and will return an unnamed function that will "capture" this binding. When calling the returned unnamed function the binding will be still alive, something impossible to achieve using simple "stack frames".
What is the most important difference between Lisp and other , Programming Languages: Chapter 6: Binding and Scope you do not know it and therefore will learn something new; ideal vehicle to study programming language concepts because it forces us LISP is a language for designing languages. ideal vehicle to study programming language concepts because it forces us to focus on fundamental language concepts; very simple and consistent, yet powerful language (see HW2DSs <= 100 LOC) Powerful languages are those which support the creation of new languages. LISP is a language for designing languages. XML is a language for designing
There are two main concepts of a binding in Lisp. I will arbitrarily call the first one traditional, perhaps wrongly, and the second one the ANSI Lisp.
The first traditional concept is that a binding is an association, in the context of some environment, between a symbol and a location which holds a value. This is exactly what is described by Kent Pitman in the paper "Technical Issues of Separation in Lisp Function Cells and Value Cells" where a definition of binding is given in these words:
A binding is a pairing of an identifier with a location in which a Lisp object may be placed.
When we evaluate a symbol, we look through the appropriate environment for a binding (starting with the lexical environment and falling back on the dynamic one, if there is such a thing). In the environment we find some cell associated with the symbol, and inside that cell is a storage box which holds a value. This is very clear. For instance, when a new lexical scope is entered during evaluation, some boxes get created and associated with symbols via entries in a new environment, and that's how we get "fresh bindings".
In ANSI Common Lisp, the above terminology is replaced by a synecdoche, whereby the ANSI CL term binding refers to just a component of the above binding: it is an association between a symbol and its value. That is to say, just the thing put into that storage box. Or alternatively, you may regard it as not a synecdoche but a higher level view: the entire mechanism which connects the variable to the box (if there is one) and from there to the value is a "binding":
binding n. an association between a name and that which the name denotes. "A lexical binding is a lexical association between a name and its value." When the term binding is qualified by the name of a namespace, such as "variable" or "function," it restricts the binding to the indicated namespace, as in: "
letestablishes variable bindings." or "
letestablishes bindings of variables." [ANSI CL Glossary Entry]
ANSI CL does not deny that there exists a storage box. For instance, all symbols in ANSI CL have a "value cell":
value cell n. Trad. (of a symbol) The place which holds the value, if any, of the dynamic variable named by that symbol, and which is accessed by symbol-value. See cell. [ANSI CL glossary entry]
It's just that the association between the symbol and the box isn't what is called a binding.
Even symbols which are not bound as dynamic variables still have a value cell (other than
NIL and keyword symbols, it goes without saying: but note that keywords support function bindings). For a dynamic variable to be unbound (as a consequence of never having been bound, or of having been subject to
makunbound) does not mean "not having a value cell".
The Common Lisp model for a dynamic binding is that the value cell either holds a value, or else somehow indicates the absence of a value. For instance the implementation can represent a value cell as an object with two slots: one holding the value, and a Boolean slot which is true if the value cell is currently bound, false if unbound. Or the value cell can have just one slot, and some special object (that only the implementation knows about, not user code) can be stored as the value in the value cell to indicate "this cell is unbound".
So, those are the two main concepts of binding: the association with a location in an environment, and the synecdochal use of "binding" as just the value of such a location. This gives rise to two possible meanings of "unbound": not to have an association to a location (no entry in the environment), or not to have an association with a value (in spite of having an association with a location in an environment).
If you're having a Lisp conversation, it helps to be clear, because these distinctions can lead to misunderstandings due to the parties using slightly different definitions.
Lisp (programming language), As in many programming languages (e.g. C/C++), LISP evaluates function calls in applicative order, Now load the definition into the LISP environment by typing: LISP will bind 1 to x, then evaluate (* x 2) before the value is bound to y. Lisp is a family of computer programming languages that originated in 1958 and has since undergone a number of changes and dialects. It is considered the second-oldest high-level programming language in use today, after Fortran. The name "Lisp" is derived from "list processing," because linked lists are part of major data structures and the
Common Lisp, This Lisp programming language will be used to execute your source code into final The parameters named as arguments within a function definition are also The handler-bind macro allows you to provide a restart function, and allows you With dynamic scoping as it's implemented in Common Lisp (and most actual languages with dynamic scoping, I think), the value of cutoff in above-cutoff?, when used as the predicate in display-if, will refer to binding b, since that's the most recent on on the stack in that case. This is shallow binding.
Programming Languages: Chapter 6: Binding and Scope, Example in Lisp: function A makes reference to a "global" variable x. Language design - fundamental aspects of the language, built-in functions, keywords. Programming - algorithms, design of data structures. The binding is determined by a linear search in the list starting from the most recent definition going backwards. Lisp is the second-oldest high-level programming language after Fortran and has changed a great deal since its early days, and a number of dialects have existed over its history. Today, the most widely known general-purpose Lisp dialects are Common Lisp and Scheme. Lisp was invented by John McCarthy
LISP Tutorial 1: Basic LISP Programming, Basic Concepts. LISP Belongs to the Functional Language Paradigm. LISP is the earliest representative of the functional programming language paradigm. Binding Time. A binding is an association between a name and the thing that is named; Binding time is the time at which an implementation decision is made to create a binding; Language design time: the design of specific program constructs (syntax), primitive types, and meaning (semantics)
- There are several different programming languages that can be said "lisp" languages (for intance Common Lisp, Scheme/Racket, Emacs Lisp, Clojure, Lisp 1.5 etc.), that have different kinds of binding. You should focus your question on some specific language (and also in that case I think this question is too broad for SO),
- (for OP) Note also that
kmulare also lexically bound, in the function namespace.