On Fri, Nov 18, 2011 at 5:02 AM, Twan van Laarhoven
* key and value function arguments passed to functions are evaluated to WHNF before the function body is evaluated, and
"function arguments passed to functions" sounds a bit redundant. Either say "arguments passed to functions" or "function arguments". Also "before the function body is evaluated" says something about evaluation order, does that really matter for strictness?
It is a bit redundant. I will remove it.
* keys and values returned by high-order function arguments are evaluated to WHNF before they are inserted into the map.
Keys and values not returned by higher order functions, but passed in directly are also evaluated to WHNF (per the first rule), so that qualification is unnecessary. Just say:
* keys and values are evaluated to WHNF before they are inserted into the map.
I don't think we have any higher-order functions that don't store evaluated keys/values in the map so this should be equivalent. Without the part about higher-order functions it's not quite clear why this second property is needed and that's why I included it to begin with. Perhaps I should instead clarify that particular part with an example.
I also think 'stored' is better here than 'inserted', because the latter might give the impression that it only applies to the insert function, and not to things like map.
'stored' is a bit more clear, I agree.
insertWith (+) k undefined m == undefined
etc.
As Roman suggested, use = here instead of ==.
I was trying to be consistent with e.g. Control.Functor etc, which use == and two surrounding spaces. I think it's good, as it avoids confusion with function declarations.
To really illustrate the first rule, insertWith (+) is not enough, you would really need a function that doesn't use the value, so
insertWith (\new old -> old) k undefined m = undefined
But that is just nitpicking.
My example is enough, but I forgot to include the side condition that k is in the map. You're example is a bit better in that it doesn't require that side condition. -- Johan