[Haskell-cafe] Confused about missing data constructor

[Bas van Dijk]

On Wed, Nov 24, 2010 at 7:08 PM, Antoine Latter <aslatter at gmail.com> wrote:
> I meant that 'pop' and 'push' should have been written with 'modify', 'get',
> and 'set' instead of the raw constructor, not as a drop-in replacement.

Indeed, you can also use the 'state' function instead of the 'State'
constructor in your definition of 'pop'.

'state' and the other "constructor functions" like 'reader' and
'writer' were introduced in mtl-2 to make the transition from mtl-1
easier.

Regards,

Bas