On 15-10-02 04:50 PM, Bardur Arantsson wrote:
On 10/02/2015 12:09 PM, Henrik Nilsson wrote:
Hi all,
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So from that perspective, using the applicative operators directly, without any syntactic sugar, actually amounts to a much more transparent and honest syntax, even if a bit more verbose in some cases.
"Verbose" is the understatement of the year. There's a lot of code where ApplicativeDo makes the difference between "readable" and "unreadable". Like it or not, but programmers are used to *naming things* (even locally) and using those local names to refer to things.
Naming of applicative sub-expressions is perfectly doable without reaching for any syntactic sugar. An applicative do like do a <- f long expression b <- g long expression return (h a b) would be equivalent to let a = f long expression b = g long expression in f <$> a <*> b The benefits of applicative do, if I understand the motivation correctly, are not so much to help in writing new code intended to be applicative. Instead it lets the programmer write in monadic style and at the same time enables the compiler to convert the code to applicative style if possible. This has the potential to automatically improve performance of legacy Haskell codebase, as well as any new beginner-friendly code that relies on syntactic sugar. As for the issue of textbooks, I assume they describe Haskell 98. Until Haskell compilers start defaulting to Haskell 2020 there shouldn't be any issue.