[Haskell-cafe] What does "1 = 2" mean in Haskell?

Brandon Allbery allbery.b at gmail.com
Fri Feb 24 02:07:42 UTC 2017

On Thu, Feb 23, 2017 at 9:05 PM, Harendra Kumar <harendra.kumar at gmail.com>

> Kids have this amazing ability to break any toy in minutes. I gave my
> seven year old daughter ghci to play with and in a little while she said it
> is broken:
> >> let 1 = 2
> >> 1
> 1
> >>
> Earlier, I had explained to her about symbols and assigning values to
> symbols, and I said numbers are not symbols. But when she came up with this
> I could not explain what's going on. How can "1 = 2" be a valid equation?
> Am I missing something fundamental here, or it is just broken?
It's a pattern match. The match fails, but as it produced no bindings it
cannot be observed and its success or failure is irrelevant.

brandon s allbery kf8nh                               sine nomine associates
allbery.b at gmail.com                                  ballbery at sinenomine.net
unix, openafs, kerberos, infrastructure, xmonad        http://sinenomine.net
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