[Haskell-cafe] What is a "simple pattern binding"?

[Simon Marlow]

On 26/06/2011 09:31, Paterson, Ross wrote:
>> If this is the case, then multiple sentences in the 2010 report don't
>> make sense, though the way in which they don't make sense sort of
>> depends on what "simple pattern binding" means.
>
> Indeed, the Report has two problems:
>
> Sections 4.4.3.2 and 4.5.5 have different definitions of "simple pattern".
> This has been there since section 4.5.5 (Monomorphism Restriction) was
> added in Haskell 1.1.  But then the only technical use of the term is
> in section 4.5.5.
>
> When the definition of declaration group (section 4.5.1) was changed in
> Haskell 2010 to break dependencies on type signatures, Rule 1 of the
> Monomorphism Restriction (section 4.5.5), while not incorrect, became
> partially redundant and overly complex.  It could have been simplified
> along the lines you describe.

Indeed, I have on my ToDo list for the Haskell report:

    Fix confusion about "simple pattern binding" terminology in Sec 4.

we should try to fix this in Haskell 2012.

Cheers,
	Simon