我在Idris玩一点形式化，我有一些奇怪的行为：一个函数的高编译时间和CPU使用率。
代码是正则表达式模式匹配算法。首先是正则表达式定义：
data RegExp : Type where
Zero : RegExp
Eps : RegExp
Chr : Char -> RegExp
Cat : RegExp -> RegExp -> RegExp
Alt : RegExp -> RegExp -> RegExp
Star : RegExp -> RegExp
Comp : RegExp -> RegExp
正则表达式成员资格和非成员资格被定义为以下相互递归的数据类型：
mutual
data NotInRegExp : List Char -> RegExp -> Type where
NotInZero : NotInRegExp xs Zero
NotInEps : Not (xs = []) -> NotInRegExp xs Eps
NotInChr : Not (xs = [ c ]) -> NotInRegExp xs (Chr c)
NotInCat : zs = xs ++ ys -> (Either (NotInRegExp xs l)
((InRegExp xs l)
,(NotInRegExp ys r)))
-> NotInRegExp zs (Cat l r)
NotInAlt : NotInRegExp xs l -> NotInRegExp xs r -> NotInRegExp xs (Alt l r)
NotInStar : NotInRegExp xs Eps ->
NotInRegExp xs (Cat e (Star e)) ->
NotInRegExp xs (Star e)
NotInComp : InRegExp xs e -> NotInRegExp xs (Comp e)
data InRegExp : List Char -> RegExp -> Type where
InEps : InRegExp [] Eps
InChr : InRegExp [ a ] (Chr a)
InCat : InRegExp xs l ->
InRegExp ys r ->
zs = xs ++ ys ->
InRegExp zs (Cat l r)
InAltL : InRegExp xs l ->
InRegExp xs (Alt l r)
InAltR : InRegExp xs r ->
InRegExp xs (Alt l r)
InStar : InRegExp xs (Alt Eps (Cat e (Star e))) ->
InRegExp xs (Star e)
InComp : NotInRegExp xs e -> InRegExp xs (Comp e)
在这些相当长的定义之后，我为替代方案定义了一个智能构造函数：
infixl 4 .|.
(.|.) : RegExp -> RegExp -> RegExp
Zero .|. e = e
e .|. Zero = e
e .|. e' = Alt e e'
现在，我想证明这个智能构造函数在正则表达式成员资格语义方面是完整的。证明几乎是简单的归纳/案例分析。但是，其中一个证明要求编译大量时间和CPU（Mac OS X El Capitan中大约90％的CPU）。
违规功能是：
altOptNotInComplete : NotInRegExp xs (Alt l r) -> NotInRegExp xs (l .|. r)
altOptNotInComplete {l = Zero} (NotInAlt x y) = y
altOptNotInComplete {l = Eps}{r = Zero} (NotInAlt x y) = x
altOptNotInComplete {l = Eps}{r = Eps} pr = pr
altOptNotInComplete {l = Eps}{r = (Chr x)} pr = pr
altOptNotInComplete {l = Eps}{r = (Cat x y)} pr = pr
altOptNotInComplete {l = Eps}{r = (Alt x y)} pr = pr
altOptNotInComplete {l = Eps}{r = (Star x)} pr = pr
altOptNotInComplete {l = Eps}{r = (Comp x)} pr = pr
altOptNotInComplete {l = (Chr x)}{r = Zero} (NotInAlt y z) = y
altOptNotInComplete {l = (Chr x)}{r = Eps} pr = pr
altOptNotInComplete {l = (Chr x)}{r = (Chr y)} pr = pr
altOptNotInComplete {l = (Chr x)}{r = (Cat y z)} pr = pr
altOptNotInComplete {l = (Chr x)}{r = (Alt y z)} pr = pr
altOptNotInComplete {l = (Chr x)}{r = (Star y)} pr = pr
altOptNotInComplete {l = (Chr x)}{r = (Comp y)} pr = pr
altOptNotInComplete {l = (Cat x y)}{r = Zero} (NotInAlt z w) = z
altOptNotInComplete {l = (Cat x y)}{r = Eps} pr = pr
altOptNotInComplete {l = (Cat x y)}{r = (Chr z)} pr = pr
altOptNotInComplete {l = (Cat x y)}{r = (Cat z w)} pr = pr
altOptNotInComplete {l = (Cat x y)}{r = (Alt z w)} pr = pr
altOptNotInComplete {l = (Cat x y)}{r = (Star z)} pr = pr
altOptNotInComplete {l = (Cat x y)}{r = (Comp z)} pr = pr
altOptNotInComplete {l = (Alt x y)}{r = Zero} (NotInAlt z w) = z
altOptNotInComplete {l = (Alt x y)}{r = Eps} pr = pr
altOptNotInComplete {l = (Alt x y)}{r = (Chr z)} pr = pr
altOptNotInComplete {l = (Alt x y)}{r = (Cat z w)} pr = pr
altOptNotInComplete {l = (Alt x y)}{r = (Alt z w)} pr = pr
altOptNotInComplete {l = (Alt x y)}{r = (Star z)} pr = pr
altOptNotInComplete {l = (Alt x y)}{r = (Comp z)} pr = pr
altOptNotInComplete {l = (Star x)}{r = Zero} (NotInAlt y z) = y
altOptNotInComplete {l = (Star x)}{r = Eps} pr = pr
altOptNotInComplete {l = (Star x)}{r = (Chr y)} pr = pr
altOptNotInComplete {l = (Star x)}{r = (Cat y z)} pr = pr
altOptNotInComplete {l = (Star x)}{r = (Alt y z)} pr = pr
altOptNotInComplete {l = (Star x)}{r = (Star y)} pr = pr
altOptNotInComplete {l = (Star x)}{r = (Comp y)} pr = pr
altOptNotInComplete {l = (Comp x)}{r = Zero} (NotInAlt y z) = y
altOptNotInComplete {l = (Comp x)}{r = Eps} pr = pr
altOptNotInComplete {l = (Comp x)}{r = (Chr y)} pr = pr
altOptNotInComplete {l = (Comp x)}{r = (Cat y z)} pr = pr
altOptNotInComplete {l = (Comp x)}{r = (Alt y z)} pr = pr
altOptNotInComplete {l = (Comp x)}{r = (Star y)} pr = pr
altOptNotInComplete {l = (Comp x)}{r = (Comp y)} pr = pr
我无法理解为什么这个功能需要这么多CPU。有没有办法优化＆＃34;这段代码是为了使编译行为正常吗？
以前的代码位于以下gist。我在Mac Os X El Capitan上使用了Idris 0.10。
非常欢迎任何线索。