Hi,

I've recently run into an issue whereby changing textual case comparison

to use the Data.CaseInsensitive.mk smart constructor causes substantial

differences to outputted core language and a related compilation speed regression.

The code which seems to cause this is here:

https://github.com/brendanhay/amazonka/blob/release/0.1.4/core/src/Network/AWS/Data/Internal/Text.hs#L51

With the downstream project having about 68 call sites for the above function starting here:

https://github.com/brendanhay/amazonka/blob/release/0.1.4/amazonka-ec2/gen/Network/AWS/EC2/Types.hs#L1465

For comparison, the previous version used Attoparsec.Text.takeText and Text values.

Here are some hand wavy points of interest:

* Before (Case Sensitive)

Function: takeText = Attoparsec.Text.takeText

Time (real): 2m27.735s

amazonka-ec2/gen/Network/AWS/EC2/Types.hs (simpl): {terms: 242,688, types: 310,463, coercions: 31,215}

* After (Case Insensitive)

Function: takeCI = Data.CaseInsensitive.mk <$> Attoparsec.Text.takeText

Time (real): 11m31.937s

amazonka-ec2/gen/Network/AWS/EC2/Types.hs (simpl): {terms: 1,384,779, types: 465,656, coercions: 33,510}

I'm finding the outputted core rather unwieldy to analyse, but the main

difference seems to be the inclusion of huge swathes of case statements like:

https://gist.github.com/brendanhay/5a57f073d5a7d196a1ad

It would be appreciated if someone could help me to understand in simple terms why

the use of case-insensitive causes this.