Hours of hacking await!
If I break, you can:
  1. Restart:           M-x haskell-process-restart
  2. Configure logging: C-h v haskell-process-log (useful for debugging)
  3. General config:    M-x customize-mode
  4. Hide these tips:   C-h v haskell-process-show-debug-tips
λ> :t ()
() :: ()
λ> :k ()
() :: *
λ> :k Maybe
Maybe :: * -> *
λ> sexpr
sexpr :: SExpr
λ> sexpr == sexpr
True
λ> sexpr == sexpr2
True
λ> printSExpr (SChar 'a')
"\\#'a'"
λ> (' ':) "abc"
" abc"
λ> printSExpr sexpr
"(2 #\\a (#t 1.2 (*** Exception: Prelude.tail: empty list
λ> printSExpr sexpr
"( 2 #\\a ( #t 1.2 ()))"
λ> printSExpr sexpr
"( 2 #\\a ( #t 1.2 ()))"
λ> countAtoms sexpr
4
λ> countAtoms sexpr
4
λ> concat [[1,2,3],[4,5,6],[7,8,9]]
[1,2,3,4,5,6,7,8,9]
λ> concat [[[1,2,3],[4,5,6],[7,8,9]]]
[[1,2,3],[4,5,6],[7,8,9]]
λ> :t concat
concat :: Foldable t => t [a] -> [a]
λ> flatten sexpr
SList {getList = [SInt 2,SChar 'a',SBool True,SDouble 1.2]}
λ> :t Data.List.concat
Data.List.concat :: Foldable t => t [a] -> [a]
λ>