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Special functions receive this name because they are different from macros and ordinary functions.
Just like macros, special functions do not evaluate their inputs. But unlike
macros, they do not return Lisp expressions that are to be evaluated. Special
functions provide the primitives on which Lisp is built, such as assignment,
conditionals, and block structure.
In 1989 [1], David S. Touretzky wrote that there were 24 built-in Common Lisp special functions:
BLOCK,
CATCH,
COMPILER-LET,
DECLARE,
EVAL-WHEN,
FLET,
FUNCTION,
GO,
IF,
LABELS,
LET,
LET*,
MACROLET,
MULTIPLE-VALUE-CALL,
MULTIPLE-VALUE-PROG1,
PROGN,
PROGV,
QUOTE,
RETURN-FROM,
SETQ,
TAGBODY,
THE,
THROW;
and, UNWIND-PROTECT.
He also said that:
This list may change with future revisions of the Common Lisp standard.
There was a new release of the book in 2014. However, the information stood the same. Even in the book in 2014, the text starts exactly like the first edition in 1989 with:
"As of mid-1989, the 24 built-in Common Lisp special functions are: ...." (page 507).
Not sure if they gave a careful look on this point, if they did, I guess they would have updated the year to be "As of mid-2014..."
Thus, as of mid-2021 is the list any different now from how it was in 1989?
Source:
[1] - COMMON LISP: A Gentle Introduction to Symbolic Computation
In the Common Lisp standard (which was published in 1994) there is no concept of a special function. The standard defines the concept of a special operator and these must not be functions. As Will Ness commented, the special operators are listed here in the Common Lisp HyperSpec (which is HTML pages derived from the standard - the original standard is published as a printed doc and a PDF file): 3.1.2.1.2.1 Special Forms. This is a fixed list -> the standard has no language mechanism provided to the Common Lisp user to add new ones. Though I think that some implementations of Common Lisp have a few additional special operators.
a form is an object meant to be evaluated: a symbol, a compound form or a self-evaluating object.
a compound form: a list with an operator or a lambda expression as the first element: a macro form, a function form, a special form or a lambda form
a special form: a compound form, which has a special operator as its first element
special operator: one of the symbols listed in chapter 3.1.2.1.2.1
Why does the book not use the terminology of the Common Lisp standard? Maybe the author was not aware of it or thought it to be too complex (or too much effort) to update the wording to use the standard wording - which would possibly mean changing a lot of things in the text.
Another useful reference is this late draft of the standard in PDF form: draft proposed ANSI CL standard. The draft has basically the same content as the published standard, but is freely available. The Common Lisp HyperSpec also has basically the same content, but in a different form.
Why does the book not use the terminology of the Common Lisp standard? Maybe the author was not aware of it or thought it to be too complex (or too much effort) to update the wording to use the standard wording - which would possibly mean changing a lot of things in the text.
I believe that the standard used an early form of CLTL, the copyright was "relaxed" to make this possible per Guy Steele Jr.
I'm calling the ListSubscribe part of the API with this json data:
{"apikey":"XXX-us2","id":"XXXXX" ,"email_address":"joe#gmail.com","double_optin":false,"merge_vars":{"GROUPINGS":{"name":"Lectures","groups":"Lecture"}}}
and I'm getting back:
{"error":"\"L\" is not a valid Interest Grouping id for the list: members-announ
ce","code":270}
However, when I use id rather than name I get pretty much the same response (the docs say both are usable). I can get things to work if I leave out the GROUPINGS call.
The following is the enumeration of the groupings:
result:
[{"id":11941,"name":"Lectures","form_field":"hidden","display_order":"0","groups
":[{"bit":"1","name":"Transit of Venus Wellington 12 June 2012","display_order":
"1","subscribers":1},{"bit":"2","name":"Transit of Venus Auckland 14 June 2012",
"display_order":"2","subscribers":1},{"bit":"4","name":"Lecture","display_order"
:"3","subscribers":0}]}]
just a quick test to do for you.
I faced this problem yesterday with c#. My mistake was on the groupings structure.
Have you try this?
"merge_vars":{"GROUPINGS": [{"name":"Lectures","groups":"Lecture"}]}
I haven't tested because I don't need for my project: this is a simple reasoning consequent to my c# experience.
Hope that works!
Here is a sample json encoding that I have tested for listUpdateMember and works without issue.
Same layout as #Sandrous but I thought I'd demonstrate the approach for naming multiple interests in a group, along with the a full json encoding.
{"apikey":"xxxx","id":"xxx","email_address":"xxx","merge_vars":{"GROUPINGS":[{"name":"Title","groups":"group1,group2,group3"}]}}
I am learning C from 'Programming in C' by Stephen Kochan.
Though the author is careful from the beginning only not to confuse the students with jargon, but occasionally he has used few terms without explaining their meaning. I have figured out the meaning of many such terms with the help of internet.
However, I could not understand the exactly meaning of the phrase 'language construct', and unfortunately the web doesn't provide a good explanation.
Considering I am a beginner, what does 'language construct' mean?
First, you need to understand what a constructed language Formal Language is. All programming languages are constructed formal languages (read the reference). You may then read a little bit about compiler construction, including this reference as well.
Going back to your question, consider this: The English language (a natural language) has tokens 'A-Z/0-9/,;"...' which we use to build "words" and we use languages rules to build sentences out of words. So, in the English language, a construct is what we build out of tokens.
Consider this brick-and-mortar example: Imagine if you set out to build a house, the basic materials you might use are: sand, iron, wood, cement, water (just five for simplicity). Anything you build out of these 4 or 5+ items would be a "construct", which in turn helps you build your house.
I have intentionally omitted details to further simplify the answer; hope this is helpful.
A language construct is a piece of language syntax. For example, the following is a language construct in C that lets you control the flow of a program:
if ( condition ) {
/* when condition is true */
} else {
/* when condition is false */
}
They usually use the term language construct because these are parts of most programming languages, but may be written differently, depending on the language. For example, a similar language construct in bourne shell would be:
if COMMAND; then
# when command returns 0
else
# when command returns anything else
fi
The function of this construct is the same, however, the way it's written is a bit different.
Hope this helps. If you need more detail, you may want to do a bit more research. As one of the comments suggests, Wikipedia may be helpful.
They are the base units from which the language is built up. They can't be used as a function rollback. They are directly called by the parser.
It includes all the syntax, semantics and coding styles of a language.
For more clarification you may refer to this question.
Wikipedia definition:
A language construct is a syntactically allowable part of a program that may be formed from one or more lexical tokens in accordance with the rules of a programming language.
The term Language Constructs is often used as a synonym for control structure, and should not be confused with a function.
Without seeing the context that the phrase is used in, I cannot be sure, but generally the phrase 'language construct' just means the combination of keywords, grammar and structure of a coding language. Basically, how to format/write/construct a piece of code.
Let say you want to create a class containing methods and properties, so:
Construct is an architecture of a class you are about to create. The architecture of the class consists of methods and properties created by you by using predefined utilities (such as: 'if', 'else', 'switch', 'break', etc)
That's my take on construct.
In reference to a programming language
Language Constructs mean the basic constructs of a programming languge e.g
1. Conditions (if, else, switch)
2. Loops (For, While, Do-while) etc
C is a structural language so while compiling your code everything thing goes statement by statement. Thus it becomes necessary to place your statement properly. This placing i.e. putting your statement correctly is your language construct else there may be syntax error or logical error.
Language constructs according to the GCSE book are basic building block of a programming language. that are
1. Sequential,
2. Selection, if, if/else
3. Iteration, while, for
Language construct is a piece of language syntax.
Example:
A declaration of a variable is a language construct:
{
int a; // declaration of a variable "a"
}
A language construct is a piece of syntax that the compiler has intimate knowledge about, usually because it needs to handle it specially. Typical examples of language constructs are the short-circuiting operators found in many imperative languages. Because these operators require lazy evaluation in an otherwise eager language, they must be handled specially by the compiler.
So, a stricter definition of a language construct may be: a syntactical form that is handled specially by the compiler, having functionality that cannot be implemented by a user.
Like Smalltalk or Lisp?
EDIT
Where control structures are like:
Java Python
if( condition ) { if cond:
doSomething doSomething
}
Or
Java Python
while( true ) { while True:
print("Hello"); print "Hello"
}
And operators
Java, Python
1 + 2 // + operator
2 * 5 // * op
In Smalltalk ( if I'm correct ) that would be:
condition ifTrue:[
doSomething
]
True whileTrue:[
"Hello" print
]
1 + 2 // + is a method of 1 and the parameter is 2 like 1.add(2)
2 * 5 // same thing
how come you've never heard of lisp before?
You mean without special syntax for achieving the same?
Lots of languages have control structures and operators that are "really" some form of message passing or functional call system that can be redefined. Most "pure" object languages and pure functional languages fit the bill. But they are all still going to have your "+" and some form of code block--including SmallTalk!--so your question is a little misleading.
Assembly
Befunge
Prolog*
*I cannot be held accountable for any frustration and/or headaches caused by trying to get your head around this technology, nor am I liable for any damages caused by you due to aforementioned conditions including, but not limited to, broken keyboard, punched-in screen and/or head-shaped dents in your desk.
Pure lambda calculus? Here's the grammar for the entire language:
e ::= x | e1 e2 | \x . e
All you have are variables, function application, and function creation. It's equivalent in power to a Turing machine. There are well-known codings (typically "Church encodings") for such constructs as
If-then-else
while-do
recursion
and such datatypes as
Booleans
integers
records
lists, trees, and other recursive types
Coding in lambda calculus can be a lot of fun—our students will do it in the undergraduate languages course next spring.
Forth may qualify, depending on exactly what you mean by "no control structures or operators". Forth may appear to have them, but really they are all just symbols, and the "control structures" and "operators" can be defined (or redefined) by the programmer.
What about Logo or more specifically, Turtle Graphics? I'm sure we all remember that, PEN UP, PEN DOWN, FORWARD 10, etc.
The SMITH programming language:
http://esolangs.org/wiki/SMITH
http://catseye.tc/projects/smith/
It has no jumps and is Turing complete. I've also made a Haskell interpreter for this bad boy a few years back.
I'll be first to mention brain**** then.
In Tcl, there's no control structures; there's just commands and they can all be redefined. Every last one. There's also no operators. Well, except for in expressions, but that's really just an imported foreign syntax that isn't part of the language itself. (We can also import full C or Fortran or just about anything else.)
How about FRACTRAN?
FRACTRAN is a Turing-complete esoteric programming language invented by the mathematician John Conway. A FRACTRAN program is an ordered list of positive fractions together with an initial positive integer input n. The program is run by updating the integer (n) as follows:
for the first fraction f in the list for which nf is an integer, replace n by nf
repeat this rule until no fraction in the list produces an integer when multiplied by n, then halt.
Of course there is an implicit control structure in rule 2.
D (used in DTrace)?
APT - (Automatic Programmed Tool) used extensively for programming NC machine tools.
The language also has no IO capabilities.
XSLT (or XSL, some say) has control structures like if and for, but you should generally avoid them and deal with everything by writing rules with the correct level of specificity. So the control structures are there, but are implied by the default thing the translation engine does: apply potentially-recursive rules.
For and if (and some others) do exist, but in many many situations you can and should work around them.
How about Whenever?
Programs consist of "to-do list" - a series of statements which are executed in random order. Each statement can contain a prerequisite, which if not fulfilled causes the statement to be deferred until some (random) later time.
I'm not entirely clear on the concept, but I think PostScript meets the criteria, although it calls all of its functions operators (the way LISP calls all of its operators functions).
Makefile syntax doesn't seem to have any operators or control structures. I'd say it's a programming language but it isn't Turing Complete (without extensions to the POSIX standard anyway)
So... you're looking for a super-simple language? How about Batch programming? If you have any version of Windows, then you have access to a Batch compiler. It's also more useful than you'd think, since you can carry out basic file functions (copy, rename, make directory, delete file, etc.)
http://www.csulb.edu/~murdock/dosindex.html
Example
Open notepad and make a .Bat file on your Windows box.
Open the .Bat file with notepad
In the first line, type "echo off"
In the second line, type "echo hello world"
In the third line, type "pause"
Save and run the file.
If you're looking for a way to learn some very basic programming, this is a good way to start. (Just be careful with the Delete and Format commands. Don't experiment with those.)
$class->method()
^
|
What's the correct terminology for this?
I've always called the symbol an "arrow".
Depends on the language:
-PHP, I believe its just used to access a class members
-C or C++ on the other hand, it is used to derefernce a pointer and access a member. It's pretty much just syntactic sugar.
pointer->member
is equivalent to
(*pointer).member
I believe that's called the "arrow notation", assuming of course you are talking about PHP. Thats what most publications, articles and the PHP website call it, so that's what my brain says on sight.
Member access operator.
I think C++ calls it “pointer member access operator.“
i would say: dereference operator
see: http://en.wikipedia.org/wiki/Dereference_operator
after some discussions with good commenters, the final terminology could be:
dereference and field access operator
that could be shorten into:
- field access operator
It's the "member selection" operator or "member by pointer" operator.
MSDN Library: C++ operators
Wikipedia: C++ opreators
In PHP it is called the T_OBJECT_OPERATOR. See the List of Parser Tokens in the PHP Manual.