Proposal: ArgumentDo

Bardur Arantsson spam at
Wed Jul 6 17:39:36 UTC 2016

On 07/04/2016 12:31 PM, Akio Takano wrote:
> Hi glasgow-haskell-users,
> I have written a wiki page about a proposed extension called
> ArgumentDo. It's a small syntactic extension that allows "do"
> expressions, lambdas and a few other kinds of expressions to be used
> as function arguments, without parentheses.
> Any feedback is appreciated. In particular, since the idea has
> received mixed support (see the "Discussion" section on the wiki
> page), I'd like to make sure that there is enough support for this
> feature to justify an implementation in GHC.


Reasons have already been given in previous threads on this. However,
I'd point especially to the fact that people don't *agree* that this is
more readable as a very strong point against -- regardless of whether
any one individual thinks it's more readable or not. The point is the
there seems to be a lot of disagreement -- that indicates to me that
this cannot by definition be a "clear win"[1]. Disclosure: I personally
find it less readable because of the implicitness. Implicitness which
has a non-trivial probability of affecting semantics is bad in my book.
Frankly, if it came to it, I'd rather just remove $ and deal with the


[1] Which I should think the barrier to extensions should roughly be :).

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