Category talk:Programming paradigm/Concatenative: Difference between revisions

:: So, for example.. J is "almost a concatenative language". It has two major departures from the [http://concatenative.org/wiki/view/Concatenative%20language fundamentals] currently described at concatenative.org: J is right to left, instead of left to right. And, composing J code requires something more than whitespace. You need <code>[: code1 code2</code> instead of just <code>code1 code2</code>. And, thus, you can get statements like <code>[: a [: b [: c [: d e</code>. (A related issue is that many of the operations which would be useful on a stack might be of the form <code>(, code)</code>. So... it's just over the edge of being a concatenative language... I think. --[[User:Rdm|Rdm]] 11:51, 8 April 2011 (UTC)

:::I think you can overlook the direction of execution for this. You could probably easily translate J to left-to-right with a few simple compiler/interpreter changes. I think that property excludes things like lazy evaluation or that some parts of the code are evaluated out of reading order. E.g. in "(2 * 3) + (4 * 5)", "2*3" and "4*5" need to be evaluated first and then the "executor" needs to "go back" and evaluate the "+" but in something like Forth the code would look like "2 3 * 4 5 * +" where everything is evaluated as it is read. An example in C-style: "function1(3, function2(4, 5))", "function1" is read, 3 is read and evaluated, function2 is read, 4 is read and evaluated, 5 is read and evaluated, function2(4, 5) is evaluated, function1(3, function2(4, 5)) is evaluated. In a concatenative language, it would be 3 4 5 function2 function1, and all parts would be evaluated as they are read from left to right. In short: it means it uses [[wp:Reverse Polish notation|RPN]] or [[wp:Polish notation|PN]]. The other fundamental...I dunno :p. --[[User:Mwn3d|Mwn3d]] 20:43, 8 April 2011 (UTC)

 

----