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When pattern matching is useful

May be that some other people want to use pattern-matching techniques in wrong ways or contexts. What I am interested in is much simpler and clear.

To be concrete, consider the use of pattern matching based transformation rules. And as an example, consider an expression that has terms of the form  exp(n/5*I*Pi), where n is an integer (from 1 to 4 say). And, for whatever reason I want to apply the rule exp(n/5*I*Pi) -> alpha^n (make it by another method is not the issue here). But 'applyrule'  (presumably  the "latest" development in this field) largely fails:

```seq(applyrule(exp(n::integer/5*I*Pi)=alpha^n,exp(i/5*I*Pi)),i=1..4);

alpha, exp(2/5 I Pi), exp(3/5 I Pi), exp(4/5 I Pi)
```

My point is that instead of so many remains of past development, pattern matching tools should be provided that work well and are maintained. There is also an issue of fragmentation and multiplication, as the absence of reliable system-wide tools make that individual packages provide their own "solution".

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