notes/pl/hs/ghc/ghci.txt

Hoogle integration:
http://www.haskell.org/haskellwiki/Hoogle#GHCi_Integration

DLL/shared libs usage:
https://www.fpcomplete.com/user/icelandj/dynamically-link-against-library-in-ghci

Config Location (of ghci.conf):

C:\Users\Ihar_Hancharenka\Application Data\ghc\
C:\Users\Ihar_Hancharenka\AppData\Roaming\

ghci commands:

:k - kind - describes the type c-tor (*, * -> *, * -> * -> *, ...)

:script $HOME/.../ghci
  include some script


:set +t
  print type after evaluation

:set +s
  print statistics (time, bytes) after evaluation

:set +m
  allow multi-line definitions
  ":{ ... :}"

:set -XNoMonomorphismRestriction
  disable monomorphism restriction

:seti ...
  set some stuff just for the repl session itself,
  not for the files we loading

********
* load *
********

:load Dir.Module
  load compiled if exists
  (:! ghc -c Module.hs)

:load *Dir.Module
  load interpreted if available
  (note: delete *.o ...)

:reload
  reload target set

! bindings go away after :load/:reload

**********
* module *
**********

:module - Dir.Module
  remove module from scope
:module + Dir1.Module1 *Dir2.Module2
  open exports from Module1
  open full scope from Module2

!standard import syntax applies as well

**********
* bro[wse] *
**********

:bro[wse] Module
  shows a module's exports
:bro[wse] *Module
  Shows full Module scope


********
* show *
********

:show modules
  list loaded modules
:show imports
  shows what's in scope
:show bindings
  List bound variables with types

********
* type *
********

:t - type
:type <expr>
  type info for an expr

********
* info *
********

:i - info and instance declarations (including priority and l/r associativity)
:info <name>
  extended information (what file/line ...)

*********
* print *
*********

:print <id>
  print without forced evaluation
  (inspect data structure at runtime)

:sprint
  like :print, but does not bind new variables
  (unevaluated subterms aren't bound to new variables, they are simply denoted by '_')
  .. print the value without causing it to be evaluated ..

:force <id>
  frint with forced evaluation

********
* bugs *
********

ghci Windows issue:
http://gloss.ouroborus.net/ (Start ghci with -fno-ghci-sandbox)


************
* debugger *
************

http://hackage.haskell.org/trac/ghc/wiki/GhciDebugger

http://www.haskell.org/ghc/docs/latest/html/users_guide/ghci-debugger.html#ghci-debugger-exceptions

>:back/forward
  to examine a step back/forward in a history

*Main> :set -fbreak-on-exception
*Main> :trace qsort ("abc" ++ undefined)
<EFBFBD>Stopped at <exception thrown>
_exception :: e
[<exception thrown>] *Main> :hist
-1  : qsort.hs:3:24-38
-2  : qsort.hs:3:23-55
-3  : qsort.hs:(1,0)-(3,55)
-4  : qsort.hs:2:15-24
-5  : qsort.hs:2:15-46
-6  : qsort.hs:(1,0)-(3,55)
<end of history>
[<exception thrown>] *Main> :back
Logged breakpoint at qsort.hs:3:24-38
_result :: [a]
as :: [a]
a :: a
[-1: qsort.hs:3:24-38] *Main> :force as
*** Exception: Prelude.undefined
[-1: qsort.hs:3:24-38] *Main> :print as
as = 'b' : 'c' : (_t1::[Char])

**********
* hoogle *
**********

ghci.conf:
:def hoogle \x -> return $ ":!hoogle \"" ++ x ++ "\""

--color
--info

********
* core *
********

ghci -dsuppress-all -ddump-simpl

*****************
* type families *
*****************

:kind! Rep (Tree ())
    show type family instance