. /. Lisp (historically, LISP) is a family of with a long history and a distinctive, fully. Originally specified in 1958, Lisp is the second-oldest in widespread use today. Only is older, by one year. Lisp has changed since its early days, and many have existed over its history.
Today, the best known general-purpose Lisp dialects are and. Lisp was originally created as a practical for, influenced by the notation of 's. It quickly became the favored programming language for (AI) research.
As one of the earliest programming languages, Lisp pioneered many ideas in, including, the, and the. The name LISP derives from 'LISt Processor'. Are one of Lisp's major, and Lisp is made of lists. Thus, Lisp programs can manipulate source code as a data structure, giving rise to the systems that allow programmers to create new syntax or new embedded in Lisp. The interchangeability of code and data gives Lisp its instantly recognizable syntax.
All program code is written as, or parenthesized lists. A function call or syntactic form is written as a list with the function or operator's name first, and the arguments following; for instance, a function f that takes three arguments would be called as ( f arg1 arg2 arg3 ). (top) and (bottom) Lisp was invented by in 1958 while he was at the (MIT). McCarthy published its design in a paper in in 1960, entitled 'Recursive Functions of Symbolic Expressions and Their Computation by Machine, Part I'. He showed that with a few simple operators and a notation for functions, one can build a language for algorithms.
Was the first AI language, from 1955 or 1956, and already included many of the concepts, such as list-processing and recursion, which came to be used in Lisp. McCarthy's original notation used bracketed ' that would be translated into.
As an example, the M-expression carconsA,B is equivalent to the S-expression ( car ( cons A B )). Once Lisp was implemented, programmers rapidly chose to use S-expressions, and M-expressions were abandoned. M-expressions surfaced again with short-lived attempts of by and. Lisp was first implemented by on an computer. Russell had read McCarthy's paper and realized (to McCarthy's surprise) that the Lisp eval function could be implemented in. The result was a working Lisp interpreter which could be used to run Lisp programs, or more properly, 'evaluate Lisp expressions.' Two for the became the primitive operations for decomposing lists: (Contents of the Address part of Register number) and (Contents of the Decrement part of Register number), where the term 'register' is used to mean 'memory register', nowadays called 'memory location'.
See for the etymology of the terms. Lisp dialects still use car and cdr ( and ) for the operations that return the first item in a list and the rest of the list respectively.
The first complete Lisp compiler, written in Lisp, was implemented in 1962 by Tim Hart and Mike Levin at MIT. This compiler introduced the Lisp model of incremental compilation, in which compiled and interpreted functions can intermix freely. The language used in Hart and Levin's memo is much closer to modern Lisp style than McCarthy's earlier code. Lisp was a difficult system to implement with the compiler techniques and stock hardware of the 1970s. Routines, developed by then- graduate student, made it practical to run Lisp on general-purpose computing systems, but efficiency was still a problem. This led to the creation of: dedicated hardware for running Lisp environments and programs.
During the 1980s and 1990s, a great effort was made to unify the work on new Lisp dialects (mostly successors to like and NIL (New Implementation of Lisp)) into a single language. The new language, was somewhat compatible with the dialects it replaced (the book notes the compatibility of various constructs). In 1994, published the Common Lisp standard, 'ANSI X3.226-1994 Information Technology Programming Language Common Lisp.' Timeline Timeline of Lisp dialects 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 Lisp 1.5 Maclisp Interlisp ZetaLisp Scheme NIL Common Lisp T Emacs Lisp AutoLISP OpenLisp PicoLisp EuLisp ISLISP newLISP Racket Guile Visual LISP Clojure Arc LFE Hy Connection to artificial intelligence Since inception, Lisp was closely connected with the research community, especially on systems.
Lisp was used as the implementation of the programming language which was used in the famous AI system. In the 1970s, as AI research spawned commercial offshoots, the performance of existing Lisp systems became a growing issue. Genealogy and variants Over its sixty-year history, Lisp has spawned many variations on the core theme of an S-expression language. Moreover, each given dialect may have several implementations—for instance, there are more than a dozen implementations of. Differences between dialects may be quite visible—for instance, Common Lisp uses the keyword defun to name a function, but Scheme uses define. Within a dialect that is standardized, however, conforming implementations support the same core language, but with different extensions and libraries. Historically significant dialects.
From the, displaying the for. LISP 1 – First implementation. LISP 1.5 – First widely distributed version, developed by McCarthy and others at MIT. So named because it contained several improvements on the original 'LISP 1' interpreter, but was not a major restructuring as the planned would be.
1.6 – This was a successor to LISP 1.5 developed at the, and widely distributed to systems running the operating system. It was rendered obsolete by Maclisp and InterLisp. – developed for MIT's (no relation to Apple's, nor to ), direct descendant of LISP 1.5.
It ran on the PDP-10 and systems. (MACLISP would later come to be called Maclisp, and is often referred to as MacLisp.).
– developed at for PDP-10 systems running the operating system, later adopted as a 'West coast' Lisp for the Xerox Lisp machines as. A small version called 'InterLISP 65' was published for the -based computer line.
For quite some time, Maclisp and InterLisp were strong competitors. – originally a project; later developed by Franz Inc. The name is a humorous deformation of the name ', and does not refer to, the dialect of Common Lisp sold by Franz Inc., in more recent years., which was based on. and were widely used and ported, especially with the Computer Algebra System REDUCE., also termed Lisp Machine Lisp – used on the, direct descendant of Maclisp.
ZetaLisp had a big influence on Common Lisp. is a French Lisp dialect. One of the first (called SOS Interface ) was written in LeLisp. (1984), as described by – a consolidation of several divergent attempts (ZetaLisp, and ) to create successor dialects to Maclisp, with substantive influences from the Scheme dialect as well. This version of Common Lisp was available for wide-ranging platforms and was accepted by many as a until the publication of ANSI Common Lisp (ANSI X3.226-1994).
was in its first version a mix of Scheme with the Common Lisp Object System. – attempt to develop a new efficient and cleaned-up Lisp. – attempt to develop a new efficient and cleaned-up Lisp.
Standardized as ISO/IEC and later revised as ISO/IEC: Information technology – Programming languages, their environments and system software interfaces – Programming language ISLISP. IEEE – IEEE standard, 1178–1990 (R1995). ANSI – an (ANSI) for Common Lisp, created by subcommittee, chartered to begin with Common Lisp: The Language as a base document and to work through a public process to find solutions to shared issues of of programs and of Common Lisp implementations. Although formally an ANSI standard, the implementation, sale, use, and influence of ANSI Common Lisp has been and continues to be seen worldwide. or 'A Computational Logic for Applicative Common Lisp', an applicative (side-effect free) variant of Common LISP. ACL2 is both a programming language which can model computer systems, and a tool to help proving properties of those models., a recent dialect of Lisp which compiles to the and has a particular focus on.
2000 to present After having declined somewhat in the 1990s, Lisp has recently experienced a resurgence of interest. Most new activity is focused around implementations of, and, and includes development of new portable libraries and applications.
Many new Lisp programmers were inspired by writers such as and to pursue a language others considered antiquated. New Lisp programmers often describe the language as an eye-opening experience and claim to be substantially more productive than in other languages. This increase in awareness may be contrasted to the ' and Lisp's brief gain in the mid-1990s. Dan Weinreb lists in his survey of Common Lisp implementations eleven actively maintained Common Lisp implementations.
Scieneer Common Lisp is a new commercial implementation forked from CMUCL with a first release in 2002. The community has created new supporting infrastructure: is a wiki that collects Common Lisp related information, the lists resources, #lisp is a popular IRC channel and allows the sharing and commenting of code snippets (with support by, an written in Lisp), collects the contents of various Lisp-related blogs, on users discuss Lisp topics, is a service for announcing job offers and there is a weekly news service,. Common-lisp.net is a hosting site for open source Common Lisp projects.
Is a library manager for Common Lisp. 50 years of Lisp (1958–2008) was celebrated at LISP50@OOPSLA.
There are regular local user meetings in Boston, Vancouver, and Hamburg. Other events include the European Common Lisp Meeting, the European Lisp Symposium and an International Lisp Conference.
The Scheme community actively maintains. Several significant new implementations (Chicken, Gambit, Gauche, Ikarus, Larceny, Ypsilon) have been developed in the last few years. The Revised 5 Report on the Algorithmic Language Scheme standard of Scheme was widely accepted in the Scheme community.
Calculator Program In C Language
The process has created a lot of quasi standard libraries and extensions for Scheme. User communities of individual Scheme implementations continue to grow. A new language standardization process was started in 2003 and led to the R 6RS Scheme standard in 2007. Academic use of Scheme for teaching computer science seems to have declined somewhat.
Some universities, such as MIT, are no longer using Scheme in their computer science introductory courses. There are several new dialects of Lisp:, and (Lisp Flavored Erlang). Major dialects and represent two major streams of Lisp development. These languages embody significantly different design choices. Is a successor to.
The primary influences were, and Scheme. It has many of the features of Lisp Machine Lisp (a large Lisp dialect used to program ), but was designed to be efficiently implementable on any personal computer or workstation. Common Lisp has a large language standard including many built-in data types, functions, macros and other language elements, as well as an object system. Common Lisp also borrowed certain features from Scheme such as and. Scheme is a statically scoped and properly tail-recursive dialect of the Lisp programming language invented by and. It was designed to have exceptionally clear and simple semantics and few different ways to form expressions. Designed about a decade earlier than Common Lisp, is a more minimalist design.
It has a much smaller set of standard features but with certain implementation features (such as and full ) not specified in Common Lisp. A wide variety of programming paradigms, including imperative, functional, and message passing styles, find convenient expression in Scheme. Scheme continues to evolve with a series of standards (Revised n Report on the Algorithmic Language Scheme) and a series of. Is a recent dialect of Lisp that principally targets the, as well as the (CLR), the, the Ruby VM, and compiling to. It is designed to be a pragmatic general-purpose language.
Clojure draws considerable influences from and places a very strong emphasis on immutability. Clojure provides access to Java frameworks and libraries, with optional type hints and, so that calls to Java can avoid reflection and enable fast primitive operations. Further, Lisp dialects are used as in many applications, with the best-known being in the editor, and later in, Nyquist in, Scheme in. The potential small size of a useful Scheme interpreter makes it particularly popular for embedded scripting. Examples include and, both of which have been successfully embedded in the image processor under the generic name 'Script-fu'.
LIBREP, a Lisp interpreter by John Harper originally based on the language, has been embedded in the. Language innovations Lisp was the first language where the structure of program code is represented faithfully and directly in a standard data structure—a quality much later dubbed '. Thus, Lisp functions can be manipulated, altered or even created within a Lisp program without lower-level manipulations. This is generally considered one of the main advantages of the language with regard to its expressive power, and makes the language suitable for syntactic macros and.
A conditional using an if-then-else syntax was invented by McCarthy in a Fortran context. He proposed its inclusion in, but it was not made part of the specification. For Lisp, McCarthy used the more general cond-structure. Took up if-then-else and popularized it. Lisp deeply influenced, the leader of the research team that developed at; and in turn Lisp was influenced by Smalltalk, with later dialects adopting object-oriented programming features (inheritance classes, encapsulating instances, message passing, etc.) in the 1970s. The object system introduced the concept of and the. The provides multiple inheritance, multimethods with, and first-class, yielding a flexible and powerful form of.
It has served as the template for many subsequent Lisp (including ) object systems, which are often implemented via a, a in which the object system is defined in terms of itself: Lisp was only the second language after Smalltalk (and is still one of the very few languages) to possess such a metaobject system. Many years later, Alan Kay suggested that as a result of the confluence of these features, only Smalltalk and Lisp could be regarded as properly conceived object-oriented programming systems. Lisp introduced the concept of, in which the system walks the looking for unused memory. Progress in modern sophisticated garbage collection algorithms such as generational garbage collection was stimulated by its use in Lisp. In his 1972 lecture said, 'With a few very basic principles at its foundation, it LISP has shown a remarkable stability. Besides that, LISP has been the carrier for a considerable number of in a sense our most sophisticated computer applications.
LISP has jokingly been described as “the most intelligent way to misuse a computer”. I think that description a great compliment because it transmits the full flavour of liberation: it has assisted a number of our most gifted fellow humans in thinking previously impossible thoughts.' Largely because of its resource requirements with respect to early computing hardware (including early microprocessors), Lisp did not become as popular outside of the community as and the -descended language. Because of its suitability to complex and dynamic applications, Lisp is enjoying some resurgence of popular interest in the 2010s.
Syntax and semantics Note: This article's examples are written in (though most are also valid in ). Symbolic expressions (S-expressions) Lisp is an. Unlike most other languages, no distinction is made between 'expressions' and; – all code and data are written as expressions. When an expression is evaluated, it produces a value (in Common Lisp, possibly multiple values), which can then be embedded into other expressions.
Each value can be any data type. McCarthy's 1958 paper introduced two types of syntax: Symbolic expressions (, sexps), which mirror the internal representation of code and data; and Meta expressions , which express functions of S-expressions. M-expressions never found favor, and almost all Lisps today use S-expressions to manipulate both code and data. The use of parentheses is Lisp's most immediately obvious difference from other programming language families. As a result, students have long given Lisp nicknames such as Lost In Stupid Parentheses, or Lots of Irritating Superfluous Parentheses. However, the S-expression syntax is also responsible for much of Lisp's power: the syntax is extremely regular, which facilitates manipulation by computer.
However, the syntax of Lisp is not limited to traditional parentheses notation. It can be extended to include alternative notations. For example, XMLisp is a Common Lisp extension that employs the to integrate S-expressions with the Extensible Markup Language. The reliance on expressions gives the language great flexibility. Because Lisp are written as lists, they can be processed exactly like data.
This allows easy writing of programs which manipulate other programs. Many Lisp dialects exploit this feature using macro systems, which enables extension of the language almost without limit. Lists A Lisp list is written with its elements separated by, and surrounded by parentheses. For example, ( 1 2 foo ) is a list whose elements are the three atoms 1, 2, and. These values are implicitly typed: they are respectively two integers and a Lisp-specific data type called a 'symbol', and do not have to be declared as such. The empty list is also represented as the special atom nil.
This is the only entity in Lisp which is both an atom and a list. Expressions are written as lists, using. The first element in the list is the name of a function, the name of a macro, a lambda expression or the name of a 'special operator' (see below). The remainder of the list are the arguments. For example, the function list returns its arguments as a list, so the expression.
( setf ( fdefinition 'f ) #' ( lambda ( a ) ( block f b. ))) Atoms In the original LISP there were two fundamental: atoms and lists. A list was a finite ordered sequence of elements, where each element is either an atom or a list, and an atom was a or a symbol. A symbol was essentially a unique named item, written as an string in, and used either as a variable name or as a data item in. For example, the list ( FOO ( BAR 1 ) 2 ) contains three elements: the symbol FOO, the list ( BAR 1 ), and the number 2. The essential difference between atoms and lists was that atoms were immutable and unique.
Two atoms that appeared in different places in source code but were written in exactly the same way represented the same objectwhereas each list was a separate object that could be altered independently of other lists and could be distinguished from other lists by comparison operators. As more data types were introduced in later Lisp dialects, and evolved, the concept of an atom lost importance. Many dialects still retained the predicate atom fordefining it true for any object which is not a cons. Conses and lists.
Box-and- diagram for the list (42 69 613) A Lisp list is. Each cell of this list is called a cons (in Scheme, a pair), and is composed of two, called the car and cdr. These are respectively equivalent to the data and next fields discussed in the article. Of the many data structures that can be built out of cons cells, one of the most basic is called a proper list. A proper list is either the special nil (empty list) symbol, or a cons in which the car points to a datum (which may be another cons structure, such as a list), and the cdr points to another proper list. If a given cons is taken to be the head of a linked list, then its car points to the first element of the list, and its cdr points to the rest of the list. For this reason, the car and cdr functions are also called first and rest when referring to conses which are part of a linked list (rather than, say, a tree).
Thus, a Lisp list is not an atomic object, as an instance of a container class in C or Java would be. A list is nothing more than an aggregate of linked conses. A variable which refers to a given list is simply a pointer to the first cons in the list. Traversal of a list can be done by cdring down the list; that is, taking successive cdrs to visit each cons of the list; or by using any of several to map a function over a list. Because conses and lists are so universal in Lisp systems, it is a common misconception that they are Lisp's only data structures.
In fact, all but the most simplistic Lisps have other data structures, such as vectors , hash tables, structures, and so forth. S-expressions represent lists Parenthesized S-expressions represent linked list structures. There are several ways to represent the same list as an S-expression. A cons can be written in dotted-pair notation as ( a. B ), where a is the car and b the cdr. A longer proper list might be written ( a.
Nil )))) in dotted-pair notation. This is conventionally abbreviated as ( a b c d ) in list notation. An improper list may be written in a combination of the two – as ( a b c. D ) for the list of three conses whose last cdr is d (i.e., the list ( a.
D ))) in fully specified form). List-processing procedures Lisp provides many built-in procedures for accessing and controlling lists. Lists can be created directly with the list procedure, which takes any number of arguments, and returns the list of these arguments. ( setf foo ( list 'a 'b 'c )) ( setf bar ( cons 'x ( cdr foo ))) the lists foo and bar are ( a b c ) and ( x b c ) respectively. However, the tail ( b c ) is the same structure in both lists. It is not a copy; the cons cells pointing to b and c are in the same memory locations for both lists.
Sharing structure rather than copying can give a dramatic performance improvement. However, this technique can interact in undesired ways with functions that alter lists passed to them as arguments. Altering one list, such as by replacing the c with a goose, will affect the other. ( setf ( third foo ) 'goose ) This changes foo to ( a b goose ), but thereby also changes bar to ( x b goose ) – a possibly unexpected result. This can be a source of bugs, and functions which alter their arguments are documented as destructive for this very reason. Aficionados of avoid destructive functions.
In the Scheme dialect, which favors the functional style, the names of destructive functions are marked with a cautionary exclamation point, or 'bang'—such as set-car! (read set car bang), which replaces the car of a cons. In the Common Lisp dialect, destructive functions are commonplace; the equivalent of set-car!
Is named rplaca for 'replace car.' This function is rarely seen however as Common Lisp includes a special facility, setf, to make it easier to define and use destructive functions. A frequent style in Common Lisp is to write code functionally (without destructive calls) when prototyping, then to add destructive calls as an optimization where it is safe to do so.
Self-evaluating forms and quoting Lisp evaluates expressions which are entered by the user. Symbols and lists evaluate to some other (usually, simpler) expression – for instance, a symbol evaluates to the value of the variable it names; ( + 2 3 ) evaluates to 5. However, most other forms evaluate to themselves: if entering 5 into Lisp, it returns 5. Any expression can also be marked to prevent it from being evaluated (as is necessary for symbols and lists). This is the role of the quote special operator, or its abbreviation ' (one quotation mark). For instance, usually if entering the symbol foo, it returns the value of the corresponding variable (or an error, if there is no such variable). To refer to the literal symbol, enter ( quote foo ) or, usually, 'foo.
Both Common Lisp and Scheme also support the backquote operator (termed in Scheme), entered with the ` character. This is almost the same as the plain quote, except it allows expressions to be evaluated and their values interpolated into a quoted list with the comma, unquote and comma-at,@ splice operators. If the variable snue has the value ( bar baz ) then ` ( foo, snue ) evaluates to ( foo ( bar baz )), while ` ( foo,@ snue ) evaluates to ( foo bar baz ). The backquote is most often used in defining macro expansions. Self-evaluating forms and quoted forms are Lisp's equivalent of literals. It may be possible to modify the values of (mutable) literals in program code.
For instance, if a function returns a quoted form, and the code that calls the function modifies the form, this may alter the behavior of the function on subsequent iterations. ( defun should-be-constant ' ( one two three )) ( let (( stuff ( should-be-constant ))) ( setf ( third stuff ) 'bizarre )); bad! ( should-be-constant ); returns (one two bizarre) Modifying a quoted form like this is generally considered bad style, and is defined by ANSI Common Lisp as erroneous (resulting in 'undefined' behavior in compiled files, because the file-compiler can coalesce similar constants, put them in write-protected memory, etc.). Lisp's formalization of quotation has been noted by (in ) and others as an example of the idea of. Scope and closure The Lisp family splits over the use of or (a.k.a. Clojure, Common Lisp and Scheme make use of static scoping by default, while, and the embedded languages in and use dynamic scoping. Since version 24.1, Emacs uses both dynamic and lexical scoping.
List structure of program code; exploitation by macros and compilers A fundamental distinction between Lisp and other languages is that in Lisp, the textual representation of a program is simply a human-readable description of the same internal data structures (linked lists, symbols, number, characters, etc.) as would be used by the underlying Lisp system. Lisp uses this to implement a very powerful macro system.
Like other macro languages such as, a macro returns code that can then be compiled. However, unlike C macros, the macros are Lisp functions and so can exploit the full power of Lisp.
Further, because Lisp code has the same structure as lists, macros can be built with any of the list-processing functions in the language. In short, anything that Lisp can do to a data structure, Lisp macros can do to code. In contrast, in most other languages, the parser's output is purely internal to the language implementation and cannot be manipulated by the programmer.
This feature makes it easy to develop efficient languages within languages. For example, the Common Lisp Object System can be implemented cleanly as a language extension using macros. This means that if an application needs a different inheritance mechanism, it can use a different object system. This is in stark contrast to most other languages; for example, Java does not support multiple inheritance and there is no reasonable way to add it. In simplistic Lisp implementations, this list structure is directly to run the program; a function is literally a piece of list structure which is traversed by the interpreter in executing it. However, most substantial Lisp systems also include a compiler.
The compiler translates list structure into machine code or for execution. This code can run as fast as code compiled in conventional languages such as C. Macros expand before the compilation step, and thus offer some interesting options. If a program needs a precomputed table, then a macro might create the table at compile time, so the compiler need only output the table and need not call code to create the table at run time. Some Lisp implementations even have a mechanism, eval-when, that allows code to be present during compile time (when a macro would need it), but not present in the emitted module.
Evaluation and the read–eval–print loop Lisp languages are often used with an interactive, which may be combined with an (IDE). The user types in expressions at the command line, or directs the IDE to transmit them to the Lisp system.
Lisp reads the entered expressions, evaluates them, and prints the result. For this reason, the Lisp command line is called a. The basic operation of the REPL is as follows.
This is a simplistic description which omits many elements of a real Lisp, such as quoting and macros. The read function accepts textual S-expressions as input, and parses them into an internal data structure. For instance, if you type the text ( + 1 2 ) at the prompt, read translates this into a linked list with three elements: the symbol +, the number 1, and the number 2.
It so happens that this list is also a valid piece of Lisp code; that is, it can be evaluated. This is because the car of the list names a function—the addition operation. Note that a foo will be read as a single symbol. 123 will be read as the number one hundred and twenty-three.
'123' will be read as the string '123'. The eval function evaluates the data, returning zero or more other Lisp data as a result.
Evaluation does not have to mean interpretation; some Lisp systems compile every expression to native machine code. It is simple, however, to describe evaluation as interpretation: To evaluate a list whose car names a function, eval first evaluates each of the arguments given in its cdr, then applies the function to the arguments. In this case, the function is addition, and applying it to the argument list ( 1 2 ) yields the answer 3. This is the result of the evaluation.
The symbol foo evaluates to the value of the symbol foo. Data like the string '123' evaluates to the same string. The list ( quote ( 1 2 3 )) evaluates to the list (1 2 3).
It is the job of the print function to represent output to the user. For a simple result such as 3 this is trivial. An expression which evaluated to a piece of list structure would require that print traverse the list and print it out as an S-expression. To implement a Lisp REPL, it is necessary only to implement these three functions and an infinite-loop function. (Naturally, the implementation of eval will be complex, since it must also implement all special operators like if or lambda.) This done, a basic REPL is one line of code: ( loop ( print ( eval ( read )))). The Lisp REPL typically also provides input editing, an input history, error handling and an interface to the debugger. Lisp is usually evaluated.
In, arguments are evaluated in ('leftmost innermost'), while in order of arguments is undefined, leaving room for optimization by a compiler. Control structures Lisp originally had very few control structures, but many more were added during the language's evolution.
(Lisp's original conditional operator, cond, is the precursor to later if-then-else structures.) Programmers in the Scheme dialect often express loops using. Scheme's commonality in academic computer science has led some students to believe that tail recursion is the only, or the most common, way to write iterations in Lisp, but this is incorrect. All oft-seen Lisp dialects have imperative-style iteration constructs, from Scheme's do loop to 's complex loop expressions. Moreover, the key issue that makes this an objective rather than subjective matter is that Scheme makes specific requirements for the handling of, and thus the reason that the use of tail recursion is generally encouraged for Scheme is that the practice is expressly supported by the language definition. By contrast, ANSI Common Lisp does not require the optimization commonly termed a tail call elimination.
Thus, the fact that tail recursive style as a casual replacement for the use of more traditional constructs (such as do, dolist or loop) is discouraged in Common Lisp is not just a matter of stylistic preference, but potentially one of efficiency (since an apparent tail call in Common Lisp may not compile as a simple ) and program correctness (since tail recursion may increase stack use in Common Lisp, risking ). Some Lisp control structures are special operators, equivalent to other languages' syntactic keywords. Expressions using these operators have the same surface appearance as function calls, but differ in that the arguments are not necessarily evaluated—or, in the case of an iteration expression, may be evaluated more than once. In contrast to most other major programming languages, Lisp allows implementing control structures using the language. Several control structures are implemented as Lisp macros, and can even be macro-expanded by the programmer who wants to know how they work. Both Common Lisp and Scheme have operators for non-local control flow. The differences in these operators are some of the deepest differences between the two dialects.
Scheme supports re-entrant using the call/cc procedure, which allows a program to save (and later restore) a particular place in execution. Common Lisp does not support re-entrant continuations, but does support several ways of handling escape continuations. Often, the same algorithm can be expressed in Lisp in either an imperative or a functional style. As noted above, Scheme tends to favor the functional style, using tail recursion and continuations to express control flow. However, imperative style is still quite possible.
The style preferred by many Common Lisp programmers may seem more familiar to programmers used to structured languages such as C, while that preferred by Schemers more closely resembles pure-functional languages such as. Because of Lisp's early heritage in list processing, it has a wide array of higher-order functions relating to iteration over sequences. In many cases where an explicit loop would be needed in other languages (like a for loop in C) in Lisp the same task can be accomplished with a higher-order function.
(The same is true of many functional programming languages.) A good example is a function which in Scheme is called map and in Common Lisp is called mapcar. Given a function and one or more lists, mapcar applies the function successively to the lists' elements in order, collecting the results in a new list. ( defun -reverse ( list ) ( let (( return-value ' )) ( dolist ( e list ) ( push e return-value )) return-value )) Object systems Various object systems and models have been built on top of, alongside, or into Lisp, including:. The, CLOS, is an integral part of ANSI Common Lisp. CLOS descended from New Flavors and CommonLOOPS. ANSI Common Lisp was the first standardized object-oriented programming language (1994, ANSI X3J13).
ObjectLisp or, used by and early versions of Macintosh Common Lisp. LOOPS (Lisp Object-Oriented Programming System) and the later., built at, and its descendant New Flavors (developed by ). KR (short for Knowledge Representation), a -based object system developed to aid the writing of Garnet, a GUI library for. (KEE) used an object system called UNITS and integrated it with an and a (ATMS). References. The Julia Manual.
Read the Docs. Archived from on 2016-04-08. Retrieved 2016-12-10. Wolfram Research. Retrieved 2016-12-10.
Reilly (2003). Greenwood Publishing Group.
Lisp is a survivor, having been in use for about a quarter of a century. Among the active programming languages only Fortran has had a longer life. Paul Graham. Retrieved 2013-03-14. Chisnall, David (2011-01-12). Jones, Robin; Maynard, Clive; Stewart, Ian (December 6, 2012).
The Art of Lisp Programming. Springer Science & Business Media. John McCarthy. Retrieved 2006-10-13. David Canfield Smith.
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Retrieved 2006-10-13. According to what reported by in, p. 185, McCarthy said: 'Steve Russell said, look, why don't I program this eval., and I said to him, ho, ho, you're confusing theory with practice, this eval is intended for reading, not for computing. But he went ahead and did it. That is, he compiled the eval in my paper into machine code, fixing, and then advertised this as a Lisp interpreter, which it certainly was. So at that point Lisp had essentially the form that it has today.'
. John McCarthy. Retrieved 2010-03-14. Tim Hart and Mike Levin.
Retrieved 2006-10-13. The 36-bit word size of the / was influenced by the usefulness of having two Lisp 18-bit pointers in a single word. Hurley (18 October 1990).:. The PDP-6 project started in early 1963, as a 24-bit machine. It grew to 36 bits for LISP, a design goal.
Common Lisp: (defun f (x) x) Scheme: (define f (lambda (x) x)) or (define (f x) x).;;;;;;;; (March 1960). (PDF).,: Artificial Intelligence Group, and. Archived from (PDF) on 2010-07-17. Accessed May 11, 2010.
McCarthy, John; Abrahams, Paul W.; Edwards, Daniel J.; Hart, Timothy P.; Levin, Michael I. (1985) 1962. (PDF) (2nd ed.). Quam, Lynn H.; Diffle, Whitfield. March 3, 1979.
Archived from on 2007-12-14. Teitelman, Warren (1974). Steele, Guy L., Jr.
Common Lisp the Language (2nd ed.). Kantrowitz, Mark; Margolin, Barry (20 February 1996). FAQ: Lisp Frequently Asked Questions 2/7. Retrieved 2013-11-15. Retrieved 2013-11-15.
Retrieved on 2013-07-17. March 24, 2009. Retrieved November 10, 2013. Broder, Evan (January 8, 2008). Retrieved November 10, 2013. Chapter 1.1.2, History, ANSI CL Standard., Retrieved 2012-06-24., Retrieved 2009-10-29.
at Sawfish Wikia, retrieved 2009-10-29. I invented conditional expressions in connection with a set of chess legal move routines I wrote in FORTRAN for the IBM 704 at M.I.T. During 1957-58.A paper defining conditional expressions and proposing their use in Algol was sent to the Communications of the ACM but was arbitrarily demoted to a letter to the editor, because it was very short. I didn't understand the monster LISP idea of tangible metalanguage then, but got kind of close with ideas about extensible languages.The second phase of this was to finally understand LISP and then using this understanding to make much nicer and smaller and more powerful and more late bound understructures.OOP to me means only messaging, local retention and protection and hiding of state-process, and extreme late-binding of all things. It can be done in Smalltalk and in LISP.
There are possibly other systems in which this is possible, but I'm not aware of them. Lieberman, Henry; Hewitt, Carl (June 1983), CACM, 26 (6): 419–429,:. Edsger W. Dijkstra (1972), (ACM Turing Award lecture). Retrieved 2006-10-13. NB: a so-called 'dotted list' is only one kind of 'improper list'.
The other kind is the 'circular list' where the cons cells form a loop. Typically this is represented using #n=(.) to represent the target cons cell that will have multiple references, and #n# is used to refer to this cons. For instance, (#1=(a b). #1#) would normally be printed as ((a b) a b) (without circular structure printing enabled), but makes the reuse of the cons cell clear. #1#) cannot normally be printed as it is circular, although (a.) is sometimes displayed, the CDR of the cons cell defined by #1= is itself. Retrieved 2013-11-15., Alan Bawden.
Retrieved on 2013-07-17. Control Abstraction (Recursion vs. Iteration) in by and, August, 1993.
pg 17 of Bobrow 1986. Veitch, p 108, 1988 Further reading. McCarthy, John (1979-02-12). History of Lisp. Stanford University. Retrieved 2008-10-17.
Steele, Jr., Guy L.; Richard P. Gabriel (1993).
The second ACM SIGPLAN conference on History of programming languages. New York, NY: ACM. Retrieved 2008-10-17. Veitch, Jim (1998).
'A history and description of CLOS'. In Salus, Peter H. Handbook of programming languages. Volume IV, Functional and logic programming languages (first ed.). Indianapolis, IN: Macmillan Technical Publishing., of 's speech, 28 October 2002, at the.
Calculator Program In Python
(2004). (March 1964). Cambridge, Massachusetts: MIT Press. Weissman, Clark (1967).
Belmont, California: Dickenson Publishing Company Inc. External links. Find more about Lisp (programming language)at Wikipedia's.
from Wiktionary. from Wikimedia Commons. from Wikiquote.
from Wikisource. from Wikibooks. from Wikiversity History. – 's history of 12 February 1979.
– Herbert Stoyan's history compiled from the documents (acknowledged by McCarthy as more complete than his own, see: ). Associations and meetings. Books and tutorials., a comic-book style introductory tutorial., a free book by., freeware edition by Peter Seibel. Interviews.
at, University of Minnesota, Minneapolis. McCarthy discusses his role in the development of time-sharing at the Massachusetts Institute of Technology. He also describes his work in artificial intelligence (AI) funded by the Advanced Research Projects Agency, including logic-based AI (LISP) and robotics. with (Podcast) Resources. (via the; archived from ). at Curlie (based on ).
Indian retail housing loan market has changed a lot in last few years. Lenders and banks are bringing innovative loan solutions to suit every individual borrower’s need and helping them to choose the loan repayment option as per his paying capacities. One such innovation is the Step-Up Loan repayment facility, which allows you to pay lower ’s in the initial years and increase them later, when your incomes levels rise and you are in a position to afford higher payments for servicing your loans.
There can essentially be two type of Step-Up Home Loans based upon the purpose. Type 1: In such type of loans, the purpose of stepping up the EMI is to reduce the loan tenure. The EMI paid in the initial years is same as the regular EMI. The increased EMI’s at later stages, when your salaries and incomes levels rise, ensures that your loan is quickly repaid and your overall interest outgo is reduced. Type 2: The purpose here is to increase your loan eligibility. The purpose of stepping up is to ensure that you are required to pay a lesser EMI in the initial years as compared to the regular EMI. This shortfall is compensated by paying higher EMI’s at later stages.
Let us elaborate them in more details with examples. Type – 1 Step Up Home Loan – Purpose is to Reduce Loan Tenure XYZ is a premium financier providing home loans to thousands of Indians. They offer a scheme with step-up repayment facility, where the EMI amount is increased by a definite step two times during the loan period – on the beginning of year 6 and on the beginning of year 11. You are given a choice to opt for any of the step up rate 5%, 10%, 15% or 20%. The calculations are as given below for a hypothetical case with following assumptions. Loan Amount = Rs.
10,00,000. Annualized interest Rate = 10%. Loan Period = 15 Months. Step up Intervals – Two times in the entire loan period. After completion of 60 months and 120 months. This means that your EMI will remain constant for first 60 months. Then it will increase by the step up rate you choose for the next 60 months.
After this 120 months, the Emi will again increase by the step up rate and then will remain same for the rest of the loan period. Step up Rate options – You can choose anything among 5%, 10%, 15% or 20%.
If we calculate the total interest paid without exercising the step up option, we find that the total loan is repaid in scheduled 180 installments and the total interest outgo is Rs. Now let us consider 4 scenarios for illustration purpose. 5% Step Up: The initial EMI comes out to be Rs. This increases by 5% to Rs. 11,283 for the next 5 years i.e. From the beginning of year 6 to the end of year 10. This again increases by 5% to Rs.
11,848 for the remaining period of the loan duration. This step up of 5% in the EMI ensures that you are able to repay your entire loan by the end of 168 installments, instead of schedules 180 installments. And your total interest outgo is Rs. 8,85,751 resulting in a saving of Rs.
10% Step Up: The initial EMI comes out to be same as earlier i.e. This increases by 10% to Rs.
11,881 for the next 5 years i.e. From the beginning of year 6 to the end of year 10. This again increases by 10% to Rs.
13,003 for the remaining period of the loan duration. This step up of 10% in the EMI ensures that you are able to repay your entire loan by the end of 158 installments, instead of schedules 180 installments. And your total interest outgo is Rs. 8,48,396 resulting in a saving of Rs. 15% Step Up: The initial EMI comes out to be same as earlier i.e.
This increases by 15% to Rs. 12,358for the next 5 years i.e.
From the beginning of year 6 to the end of year 10. This again increases by 15% to Rs. 14,212 for the remaining period of the loan duration.
This step up of 15% in the EMI ensures that you are able to repay your entire loan by the end of 158 installments, instead of schedules 151 installments. And your total interest outgo is Rs. 8,18,629 resulting in a saving of Rs. 20% Step Up: The initial EMI comes out to be same as earlier i.e. This increases by 20% to Rs.
12,895 for the next 5 years i.e. From the beginning of year 6 to the end of year 10. This again increases by 20% to Rs. 15,474 for the remaining period of the loan duration. This step up of 20% in the EMI ensures that you are able to repay your entire loan by the end of 158 installments, instead of schedules 180 installments. And your total interest outgo is Rs.
7,94,186 resulting in a saving of Rs. +%3Pfgebat%3R%3Pn+uers%3Q%22uggc%3N%2S%2Sybnapnyphyngbef.va%2Sqbjaybnqf%2Sfgrc-hc-ybna-pnyphyngbe.kyfk%22%3RLbhe+Qbjaybnq+Yvax%3P%2Sn%3R%3P%2Sfgebat%3R+Gunaxf+sbe+Yvxvat+Hf.+Cyrnfr+funer+vg+jvgu+lbhe+sevraqf+ba+Snprobbx+ol+jevgvat+va+gur+Snprobbx+obk+nobir.+ Type -2 Step Up Home Loan – The Purpose is to Increase Home Loan Eligibility As already mentioned earlier, the purpose of stepping up of EMI in such type of loans is to ensure that you are required to pay a lesser EMI in the initial years as compared to the regular EMI. This shortfall is compensated by paying higher EMI’s at later stages. The lower initial EMI’s in the initial years essentially mean that the major part of the initial EMI’s is used up only to serve the interest dues and there is very little left for principal repayment. This results in very slow rate of reduction in the outstanding loan and ultimately higher total interest outgo from your pocket.
You should choose this option only when you are looking to get a higher loan from the lender, which you may not afford in a regular (without step-up facility) with your current income levels. A key risk in this type of step-up home loan repayment schedule is the future volatility in the interest rate.
Nobody can accurately predict the economic cycles and so, you cannot determine when the interest rate cycle start moving in northward direction. If this happens abruptly, this might significantly increase your EMI’s in future, which you may not be able to sustain. You should factor this aspect, while choosing step-up loan option with a purpose of increasing your loan eligibility. Because of this inherent risk involved, Type-2 Step Up Home loans are generally not offered to business men. They are provided to salaried persons and professionals, whose income levels are expected to grow over a period of time in a more predictable manner.
Within that segment also, this loan is more suitable for borrowers of younger generations, who might safely expect their incomes to rise quickly in near future.