Feature request: Multiline input for eval plugin

[septatrix]

I have tried to get multiline inputs working for the eval plugin however to no avail. What I would like is support for the following syntax:

>>> tree = :{ Node 9 [
>>>     Leaf 5,
>>>     Leaft 12
>>> ] :}
-- or
>>> :set +m
>>> tree = Node 9 [
>>>     Leaf 5,
>>>     Leaft 12
>>> ]

However this always results in an exception like parse error on input ‘:’ and parse error (possibly incorrect indentation or mismatched brackets) respectively.

[merc1031]

with HLS 1.5.1 i see a similar issue

>>> :{
 let a = 1
 in a
 :}

gets replaced with

>>> :{
unknown command '{'

when evaluated

same with the example from the doc https://hackage.haskell.org/package/hls-eval-plugin-1.2.0.2

>>> :{
  let
    x = 1
    y = 2
  in x + y + multiline
 :}

is replaced with

>>> :{
unknown command '{'