[Haskell-cafe] How to create a list of each constructor value

[Joachim Breitner]

Hi,

Am Samstag, dem 03.12.2022 um 20:12 +0100 schrieb Henning Thielemann:
> > if you want to golf it a bit more, then
> > 
> >    [minBound..]
> > 
> > works as well.
> 
> Wouldn't this create an infinite tail of undefined value

That’s what I thought until I learned about this. Anyways, ghci says it
doesn’t:

   ghci> [False .. ]
   [False,True]
   ghci> [LT .. ]
   [LT,EQ,GT]
   
[x..] is just enumFrom x, and the docs for Enum says

> enumFrom and enumFromThen should be defined with an implicit bound,

https://hackage.haskell.org/package/base-4.17.0.0/docs/Prelude.html#t:Enum

Cheers,
Joachim


-- 
Joachim Breitner
  mail at joachim-breitner.de
  http://www.joachim-breitner.de/