[Haskell-cafe] Printing call site for partial functions

Henk-Jan van Tuyl hjgtuyl at chello.nl
Mon Apr 30 11:33:54 CEST 2012

On Mon, 30 Apr 2012 10:31:01 +0200, Ketil Malde <ketil at malde.org> wrote:

> One half-baked quasi-solution is to use:
> #define head (\xs -> case xs of { (x:_) -> x ; _ -> error("head: empty  
> list at"++__FILE__++show __LINE__)})
> Downsides are that it depends on CPP, and, CPP being a C preprocessor,
> it doesn't blend well with lines with single apostrophes on them (e.g.:
> head x')
> -k

There is a Haskell solution: cpphs[0], you can invoke this preprocessor by  
specifying the flags
   -cpp  -pgmPcpphs  -optP--cpp
for GHC.

Henk-Jan van Tuyl

[0] http://hackage.haskell.org/package/cpphs

Haskell programming

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