[Haskell-cafe] Haskell Cheat Sheet?
westondan at imageworks.com
Wed Sep 26 14:43:45 EDT 2007
It seems no one liked idea #2. I still think fix is the wrong name for
this, maybe limit would be better.
Dan Weston wrote:
> One suggestion:
> Section 3.6 defines a function "fix":
> fix :: Eq x => (x -> x) -> x -> x
> fix f x = if x == x' then x else fix f x'
> where x' = f x
> This confusingly differs in both type and meaning from the traditional
> function Control.Monad.Fix.fix and is not even used elsewhere in the
> I suggest that it be removed and the real Control.Monad.Fix.fix function
> be defined in its own section, with an side-by-side comparison with a
> named recursive function. This would be useful because the type
> fix :: (a -> a) -> a
> is highly confusing, suggesting to newcomers a usage like:
> f = fix (+1)
> which is undefined (and seems to be "missing an argument"), when
> invariably its type is in practice restricted to:
> fix :: ((a -> b) -> (a -> b)) -> (a -> b)
> which is much more suggestive (but nowhere to be found in the docs).
> Dan Weston
> Don Stewart wrote:
>>> Has anybody made (or have a link to) a Haskell reference cheat sheet?
>>> I'm thinking of a nice LaTeXed PDF in the 1-10 page range (e.g.
>>> something like this http://www.tug.org/texshowcase/cheat.pdf) with the
>>> basics of the language syntax, the type declarations for the common type
>>> classes, the type signatures of the most commonly used functions in the
>>> Prelude and other common modules, and so forth? The Haskell standard
>>> library is very large for a newcomer (even just the Prelude!), and as a
>>> learner of the language I find myself spending a lot of time looking up
>>> Prelude functions and syntax details -- having all of this in a short
>>> PDF document that I could have offline would be very useful.
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