Introduction to APL - Revision history

Paul Robinson: make minor changes to correct errors

2019-10-16T15:32:04Z

make minor changes to correct errors

← Older revision		Revision as of 11:32, 16 October 2019
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	Welcome to the wonderful world of APL. Whether you've never done programming before or you're a journeyman programmer, APL is going to be something new to you. APL works like no other programming language. First, if you've done any programming, you "know" that when you have an assignment or something like a piece of code is executed, it's "always" done right ~~to left~~ and mathematical formulas are always evaluated right ~~to left~~ according to precedence, so that exponentiation is done first, then multiplication and division, then addition and subtraction. Well, APL is going to blow you away because ''everything you know is wrong''.		Welcome to the wonderful world of APL. Whether you've never done programming before or you're a journeyman programmer, APL is going to be something new to you. APL works like no other programming language. First, if you've done any programming, you "know" that when you have an assignment or something like a piece of code is executed, it's "always" done left to right and mathematical formulas are always evaluated left to right according to precedence, so that exponentiation is done first, then multiplication and division, then addition and subtraction. Well, APL is going to blow you away because ''everything you know is wrong''.

	First, APL is "backwards" to what you know. APL operates from ''right to left''. All other programming languages operate from left to right. When it comes to computing mathematical formulas, APL has no precedence; unless you put something in parenthesis, all mathematical computations are done strictly right to left to produce the result.		First, APL is "backwards" to what you know. APL operates from ''right to left''. All other programming languages operate from left to right. When it comes to computing mathematical formulas, APL has no precedence; unless you put something in parenthesis, all mathematical computations are done strictly right to left to produce the result.

Paul Robinson: add cat

2019-10-16T15:22:30Z

add cat

← Older revision		Revision as of 11:22, 16 October 2019
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	* [[Operators]]		* [[Operators]]
	* [[Language_Features]]		* [[Language_Features]]

			[[Category:Examples]]

WikiSysop at 16:45, 28 April 2018

2018-04-28T16:45:49Z

← Older revision		Revision as of 12:45, 28 April 2018
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	Now, that by itself isn't very exciting. But what if you had an array X of 1000 numbers. In C you'd have to do something like<br/>		Now, that by itself isn't very exciting. But what if you had an array X of 1000 numbers. In C you'd have to do something like<br/>
	<code>		<code>
	k == 0;~~<br/>~~		k == 0;
	for (i=1;i++;i<1001) {~~<br/>~~		for (i=1;i++;i<1001) {
	k += X[i];~~<br/>~~		k += X[i];
	}</code>~~<br>~~		}</code>

	You'd do the same thing in APL with		You'd do the same thing in APL with
	: k {:=} +/ X		: k {:=} +/ X

Robert Wallick: Filled in operators, primitives, etc. links

2016-02-08T17:22:45Z

Filled in operators, primitives, etc. links

← Older revision		Revision as of 13:22, 8 February 2016
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	APL will take all of the entries in the array X and sum them, in one instruction. You don't even have to know how many entries are in the array X; APL will handle it for you.		APL will take all of the entries in the array X and sum them, in one instruction. You don't even have to know how many entries are in the array X; APL will handle it for you.

	To be able to program in APL you'll have to learn what all of the operators do. ~~A link~~ to ~~a page~~ describing ~~each symbol~~ and what ~~it does~~, ~~is shown~~ below.		To be able to program in APL you'll have to learn what all of the operators do. Links to pages describing APL/APL2 symbols and what they do, just below:
			* [[Operators]]
	~~-- To be done --~~		* [[Language_Features]]

Paul Robinson at 08:19, 9 March 2013

2013-03-09T08:19:49Z

← Older revision		Revision as of 04:19, 9 March 2013
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	Welcome to the wonderful world of APL. Whether you've never done programming before or you're a journeyman programmer, APL is going to be something new to you. APL works like no other programming language. First, ~~APL operates from right to left. All other~~ programming ~~languages operate from left to right. When it comes to computing mathematical formulas~~, ~~APL has no precedence; unless~~ you ~~put~~ something ~~in parenthesis~~, ~~all~~ mathematical ~~computations~~ are ~~done strictly~~ right to left to ~~produce the result~~.		Welcome to the wonderful world of APL. Whether you've never done programming before or you're a journeyman programmer, APL is going to be something new to you. APL works like no other programming language. First, if you've done any programming, you "know" that when you have an assignment or something like a piece of code is executed, it's "always" done right to left and mathematical formulas are always evaluated right to left according to precedence, so that exponentiation is done first, then multiplication and division, then addition and subtraction. Well, APL is going to blow you away because ''everything you know is wrong''.

	Also, APL uses a specialized keyboard. Many of the actions you have to write a program in other languages can be done in one character in APL. While your typical programming language would show 3 times 4 as '''3*4''', APL has a multiply symbol, so it is written as '''3{times}4''', and to create one half or '''1/2''' in most languages, in APL you would enter '''1{divide}2''' .		First, APL is "backwards" to what you know. APL operates from ''right to left''. All other programming languages operate from left to right. When it comes to computing mathematical formulas, APL has no precedence; unless you put something in parenthesis, all mathematical computations are done strictly right to left to produce the result.

			Also, APL uses a specialized set of symbols, and before we had graphical systems, it even had its own specialized keyboard. Many of the actions you have to write a program in other languages can be done in one character in APL. While your typical programming language would show 3 times 4 as '''3*4''', APL has a multiply symbol, so it is written as '''3{times}4''', and to create one half or '''1/2''' in most languages, in APL you would enter '''1{divide}2''' .

	So, for example, if you have the following mathematical expression		So, for example, if you have the following mathematical expression
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	To be able to program in APL you'll have to learn what all of the operators do. A link to a page describing each symbol and what it does, is shown below.		To be able to program in APL you'll have to learn what all of the operators do. A link to a page describing each symbol and what it does, is shown below.

	-- To be ~~added~~ --		-- To be done --

Paul Robinson at 00:19, 1 March 2013

2013-03-01T00:19:54Z

← Older revision		Revision as of 20:19, 28 February 2013
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	: k {:=} +/ X		: k {:=} +/ X
	APL will take all of the entries in the array X and sum them, in one instruction. You don't even have to know how many entries are in the array X; APL will handle it for you.		APL will take all of the entries in the array X and sum them, in one instruction. You don't even have to know how many entries are in the array X; APL will handle it for you.

			To be able to program in APL you'll have to learn what all of the operators do. A link to a page describing each symbol and what it does, is shown below.

			-- To be added --

Paul Robinson at 06:38, 23 February 2013

2013-02-23T06:38:10Z

← Older revision		Revision as of 02:38, 23 February 2013
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	So, for example, if you have the following mathematical expression		So, for example, if you have the following mathematical expression
	: 4 {times} 5 - 10		: 4*5-10 (in normal programming languages), or in APL: 4 {times} 5 - 10
	Your typical programming language would compute it as 4{times}5 which is (20), then 20 - 10, resulting in 10. APL will compute it as 5-10 (-5) * 4, or -20. You can adjust this by placing arguments within parenthesis. If your expression was written as		Your typical programming language would compute it as 4{times}5 which is (20), then 20 - 10, resulting in 10. APL will compute it as 5-10 (-5) * 4, or -20. You can adjust this by placing arguments within parenthesis. If your expression was written as
	: (4 {times} 5) - 10		: (4 {times} 5) - 10

Paul Robinson at 22:36, 22 February 2013

2013-02-22T22:36:14Z

← Older revision		Revision as of 18:36, 22 February 2013
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	<code>		<code>
	k == 0;<br/>		k == 0;<br/>
	for (i=0;i++;i<~~1000~~) {<br/>		for (i=1;i++;i<1001) {<br/>
	k += X[i];<br/>		k += X[i];<br/>
	}</code><br>		}</code><br>

Paul Robinson at 22:34, 22 February 2013

2013-02-22T22:34:57Z

← Older revision		Revision as of 18:34, 22 February 2013
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	It would produce the same answer no matter what programming language you use.		It would produce the same answer no matter what programming language you use.

	Where APL shines is its ability to handle arrays as easily as most programs handle single values. For example, the '''plus reduce''' operator is used to sum a list of numbers, so in a typical programming language like c you'd have		Where APL shines is its ability to handle arrays as easily as most programs handle single values. For example, the '''plus reduce''' operator is used to sum a list of numbers, so in a typical programming language like C or C++ you'd have
	: K == 5 + 6 + 8 + 9 + 12 +14		: K == 5 + 6 + 8 + 9 + 12 +14
	In APL, you'd do the same thing with		In APL, you'd do the same thing with
	: K {:=} +/5 6 8 9 12 14		: K {:=} +/5 6 8 9 12 14
			Now, that by itself isn't very exciting. But what if you had an array X of 1000 numbers. In C you'd have to do something like<br/>
			<code>
			k == 0;<br/>
			for (i=0;i++;i<1000) {<br/>
			k += X[i];<br/>
			}</code><br>
			You'd do the same thing in APL with
			: k {:=} +/ X
			APL will take all of the entries in the array X and sum them, in one instruction. You don't even have to know how many entries are in the array X; APL will handle it for you.

Paul Robinson at 22:26, 22 February 2013

2013-02-22T22:26:26Z

← Older revision		Revision as of 18:26, 22 February 2013
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	Also, APL uses a specialized keyboard. Many of the actions you have to write a program in other languages can be done in one character in APL. While your typical programming language would show 3 times 4 as '''3*4''', APL has a multiply symbol, so it is written as '''3{times}4''', and to create one half or '''1/2''' in most languages, in APL you would enter '''1{divide}2''' .		Also, APL uses a specialized keyboard. Many of the actions you have to write a program in other languages can be done in one character in APL. While your typical programming language would show 3 times 4 as '''3*4''', APL has a multiply symbol, so it is written as '''3{times}4''', and to create one half or '''1/2''' in most languages, in APL you would enter '''1{divide}2''' .



	So, for example, if you have the following mathematical expression		So, for example, if you have the following mathematical expression
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	: (4 {times} 5) - 10		: (4 {times} 5) - 10
	It would produce the same answer no matter what programming language you use.		It would produce the same answer no matter what programming language you use.

			Where APL shines is its ability to handle arrays as easily as most programs handle single values. For example, the '''plus reduce''' operator is used to sum a list of numbers, so in a typical programming language like c you'd have
			: K == 5 + 6 + 8 + 9 + 12 +14
			In APL, you'd do the same thing with
			: K {:=} +/5 6 8 9 12 14