Differences between current version and revision by previous author of Aym.
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| Newer page: | version 6 | Last edited on Friday, November 24, 2006 5:58:21 pm | by AlastairPorter | |
| Older page: | version 5 | Last edited on Wednesday, March 16, 2005 11:44:52 am | by CraigBox | Revert |
@@ -3,32 +3,40 @@
!A Really Bad Example
Aym Specification:
+<pre>
function sum(x) of type integer returning integer
let sum(0) = 0
let sum(x) = x + sum(x-1)
+</pre>
C++ Implementation:
+<pre>
int sum( int x )
{
int count = 0;
for(int i = 0; i<x; i++) {
count += i;
}
return count;
}
+</pre>
Notice that these two functions return completely different results! The idea is that the unit-testing portion of the project would catch this and inform you of the input, expected output and actual output.
-[Aym] also supports the idea of "watches", whereby __internal__ values of the specification and implementation can be made to match, not just returned results. This is facilitated by the use of a function ''!
AymWatch'', of type string * 'a -> 'a. Using the above example again, one might insert a watch into the last line of the specification such as:
+[Aym] also supports the idea of "watches", whereby __internal__ values of the specification and implementation can be made to match, not just returned results. This is facilitated by the use of a function ''~
AymWatch'', of type string * 'a -> 'a. Using the above example again, one might insert a watch into the last line of the specification such as:
-
let sum(x) = !
AymWatch("sumwatch", x) + sum(x-1)
+<pre>
+
let sum(x) = ~
AymWatch("sumwatch", x) + sum(x-1)
+</pre>
And then the implementation would have a line added to it such as:
- !
AymWatch("sumwatch", i);
+<pre>
+ ~
AymWatch("sumwatch", i);
+</pre>
The unit-testing framework will ensure that the values match at each update.
Aym is GPLish. If you want a copy (''why?''), talk to GianPerrone or AlastairPorter.
