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| Newer page: | version 20 | Last edited on Wednesday, July 4, 2007 1:26:03 pm | by GlynWebster | Revert |
| Older page: | version 18 | Last edited on Monday, January 19, 2004 6:26:30 am | by AristotlePagaltzis | Revert |
@@ -1,45 +1,45 @@
An imperative ProgrammingLanguage designed by NicolasWirth as a teaching language. Once very popular in schools before students started whining that they wanted to learn [C]. The ancestor of the language in [Borland]'s [Delphi] and [Kylix] [GUI] development environments, which added ObjectOrientation.
!!! A Sample
- __
function__
plural (noun : __
string__
) : __
string__
;
-
{ Returns the plural version of a noun. }
- __
var__
-
i : integer;
- __
begin__
- __
case__
noun[[length(noun)] __
of__
-
's': __
if__
noun[[length(noun)-1] = 'e' __
then__
-
plural := noun
- __
else__
-
plural := noun + 'es';
-
'y': __
begin__
-
delete(noun, length(noun), 1);
-
plural := noun + 'ies';
- __
end__
;
- __
else__
plural := noun + 's';
- __
end__
;
- __
end__
; {plural}
+<verbatim>
+
function plural (noun : string) : string;
+
{ Returns the plural version of a noun. }
+var
+
i : integer;
+begin
+
case noun[[length(noun)] of
+
's': if noun[[length(noun)-1] = 'e' then
+
plural := noun
+
else
+
plural := noun + 'es';
+
'y': begin
+
delete(noun, length(noun), 1);
+
plural := noun + 'ies';
+
end;
+
else plural := noun + 's';
+
end;
+end; {plural}
+</verbatim>
(This is in the TurboPascal dialect of Pascal.)
!!! History
-Pascal became popular very quickly because the original compiler was designed to be very easy to [Port]. It was written in Pascal and compiled to [ByteCode]s, called ''P-Code''. All anyone had to do to get a Pascal compiler working on a new machine was to write the simple P-Code VirtualMachine for it -- they could hack the compiler around to generate proper MachineCode later. This meant that Pascal spread very quickly through the world's Universities. They began teaching in Pascal, because
it was a very good language to demonstrate
structured programming in -- a new idea and as such
a hot topic at the time.
+Pascal became popular very quickly because the original compiler was designed to be very easy to [Port]. It was written in Pascal and compiled to [ByteCode]s, called ''P-Code''. All anyone had to do to get a Pascal compiler working on a new machine was to write the simple P-Code VirtualMachine for it -- they could hack the compiler around to generate proper MachineCode later. This meant that Pascal spread very quickly through the world's Universities. They soon
began teaching in Pascal --
it was a very good language for demonstrating
structured programming,
a hot topic at the time.
-Standard Pascal was a nice language with terrible limitations: Pascal programs could not open files by name, could barely handle strings and could only pass arrays of predetermined sizes to functions. BrianKernighan famously described Pascal's problems in [Why Pascal is Not My Favorite Programming Language |http://www.lysator.liu.se/c/bwk-on-pascal.html]. It has to be noted that NicolasWirth had already addressed most of Pascal's problems in his follow-up language [Modula2] ''before'' BrianKernighan
wrote this paper. In
some places BrianKernighan
seems to be just complaining that Pascal is not [C]. At any rate, these limitations meant that Pascal splintered into dialects as people hacked in missing features in incompatible ways. [C] did not have this problem, so it gradually took over from the Pascal dialects.
+Standard Pascal was a nice language with terrible limitations: Pascal programs could not open files by name, could barely handle strings and could only pass arrays of predetermined sizes to functions. BrianKernighan famously described Pascal's problems in [Why Pascal is Not My Favorite Programming Language |http://www.lysator.liu.se/c/bwk-on-pascal.html]. (
It has to be noted that NicolasWirth had already addressed most of Pascal's problems in his follow-up language [Modula2] ''before'' Kernighan
wrote this paper, and in
some places Kernighan
seems to be just complaining that Pascal is not [C].)
At any rate, these limitations meant that Pascal splintered into dialects as people hacked in missing features in incompatible ways. [C] did not have this problem, so it gradually took over from the Pascal dialects.
!!! Implementations
-
-The Pascal grammer has maps very nicely to a RecursiveDescentParser struture and for this reason in it the language of choice when writing a RecursiveDescentParser by hand.
The most successful Pascal dialect has been Borland's TurboPascal. There are two OpenSource Pascal compilers for [Linux]:
* [GNU Pascal | http://www.gnu-pascal.de/]
* [Free Pascal | http://www.freepascal.org/]
Free Pascal tends more towards TurboPascal compatibility.
-The online book [Pascal Implementation: A Book and Sources | http://www.cwi.nl/~steven/pascal/] walks you through the source code to the original Pascal compiler. It's educational to read just as an extended critique of a non-trivial program.
+The online book [Pascal Implementation: A Book and Sources | http://www.cwi.nl/~steven/pascal/] walks you through the source code to the original Pascal compiler (implemented in Pascal as a RecursiveDescentParser)
. It's educational to read just as an extended critique of a non-trivial program.
-----
Part of CategoryProgrammingLanguages, CategoryImperativeProgrammingLanguages, CategoryMachineOrientedProgrammingLanguages
