[Haskell-cafe] Origins of (x:xs)?

Paul Hudak paul.hudak at yale.edu
Tue Dec 19 17:54:54 EST 2006

Pattern matching goes back to Burstall and Darlington's work in the 1970's.

As for "x:xs", the "xs" is meant to be the plural of "x", and is 
pronounced "exs" (I guess...).
Similarly, "n:ns" is one n followed by many more "ens".   Make sense?

(By the way, ":" is often pronounced "followed by".)

    -Paul Hudak

Toby Hutton wrote:
> Hi,
> This may have been asked before, sorry if so.  I've wondered where the 
> convention of pattern matching a list to (x:xs) came from?  I've read 
> a couple of old papers recently which let me believe it may have 
> started back in the '70s with Miranda and its ilk.
> Does anyone know why (x:xs)?  Is xs meant to be a synonym for 'excess'?
> Yours curiously,
> Toby.

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