[Haskell-cafe] Fwd: 'let' keyword optional in do notation?

Martijn Schrage martijn at oblomov.com
Thu Aug 16 17:53:22 CEST 2012

On 09-08-12 10:35, Tillmann Rendel wrote:
> Hi,
> Martijn Schrage wrote:
>>> Would expanding each let-less binding to a separate let "feel" more
>>> sound to you?
>> That was actually my first idea, but then two declarations at the same
>> level will not be in the same binding group, so
>> do x = y
>>    y = 1
>> would not compile. This would create a difference with all the other
>> places where bindings may appear.
> But it would be in line with <- bindings in the do notation, so maybe 
> it wouldn't feel so wrong.
It would absolutely be the easiest solution to implement, since as far 
as I can see, it requires only a small change to the parser. However, I 
still think it will be too confusing to have bindings that look the same 
as everywhere else but have different binding group rules. Especially 
since there is no reason for it from a semantic point of view (unlike 
when you mix in a monadic <- binding, after which it makes sense to have 
a new binding group.)

Anyhow, I'll submit it as a GHC feature request and see what happens.

Martijn Schrage -- Oblomov Systems (http://www.oblomov.com)
>   Tillmann
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