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

Martijn Schrage martijn at oblomov.com
Wed Aug 8 19:50:14 CEST 2012

On 08-08-12 19:01, Simon Hengel wrote:
> On Wed, Aug 08, 2012 at 12:22:39PM -0400, David Feuer wrote:
>> Changing scoping rules based on whether things are right next to each
>> other? No thanks.
> 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.

However, having scope depend on things being next to each other (or 
rather, not having anything in between) is not new. Template Haskell 
declaration splices already cause separate binding groups for top-level 
declarations. Moreover, the new scope rule only holds for let-less 
bindings. If you use explicit lets nothing changes.

-- Martijn
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