Could we have multiline expectations?

[philderbeast]

Could we have multiline expectations (when GHC gets multiline strings ghc-proposals/ghc-proposals#569)?

-- >>> render . docProjectConfigPath $ ProjectConfigPath $ "D.config" :| ["C.config", "B.config", "A.project" ]
-- "D.config\n  imported by: C.config\n  imported by: B.config\n  imported by: A.project"

This would then become something like;

-- >>> render . docProjectConfigPath $ ProjectConfigPath $ "D.config" :| ["C.config", "B.config", "A.project" ]
-- """
-- D.config
--  imported by: C.config
--  imported by: B.config
--  imported by: A.project
-- """

The snippet is taken from haskell/cabal#9578.

[sol]

@philderbeast with GHC 9.10.1 out, can this output be produced by GHCi? If yes, then I think it should already work, if no then it may be out-of-scope for doctest. doctest is a tool to verify that example GHCi sessions work. It's a documentation tool, not primarily a testing tool. Hspec is a better option for testing.

[sol]

Reconsidering this, what we may do is:

1. Compare actual and expected verbatim
2. If verbatim comparison fails, then try to parse actual and expected into a Haskell AST. If parsing for both succeeds, then compare the ASTs.

This would then also enable things like:

>>> [1..3]
[1, 2, 3]
-- instead of [1,2,3]

or

>>> person
Person {
  name = "Joe"
, age = 23
}
-- instead of Person {name = "Joe", age = 23}

[philderbeast]

with GHC 9.10.1 out, can this output be produced by GHCi?

It looks like we'd need at least GHC 9.12.1 for multiline strings.