The present package

[Tags:bsd3, library]

Make presentations for data types.

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Versions 0.0.0, 1.0, 1.1, 2.0, 2.1, 2.2, 4.0.0, 4.0.1, 4.0.2 (info)
Dependencies base (==4.*), template-haskell [details]
License BSD3
Copyright 2016 Chris Done
Author Chris Done
Stability Unknown
Category Development
Home page
Uploaded Fri Mar 25 22:28:10 UTC 2016 by ChrisDone
Distributions NixOS:4.0.2
Downloads 2457 total (25 in the last 30 days)
0 []
Status Docs not available [build log]
All reported builds failed as of 2016-11-27 [all 2 reports]


  • Present


Maintainer's Corner

For package maintainers and hackage trustees

Readme for present

Readme for present-4.0.2


Make presentations for data types.


Requires: GHC 7.10.3

Install globally into your GHC's global database (via stack) with:

$ sh

To remove it later:

$ sh

To be added: install via stack install present, but it needs to be added to an LTS/nightly version first.

Customizing GHCi

Add to the following to your ~/.ghci:

:seti -XTemplateHaskell
:def presentDebug \e -> return ("let it = " ++ e ++ "\n$(Present.presentIt)")
:def presentQualified \e -> return ("let it = " ++ e ++ "\nPrelude.putStrLn (Present.toShow True $(Present.presentIt))")
:def present \e -> return ("let it = " ++ e ++ "\nPrelude.putStrLn (Present.toShow False $(Present.presentIt))")
:set -package present


bash-3.2$ stack exec ghci
GHCi, version 7.10.3:  :? for help
package flags have changed, resetting and loading new packages...
λ> :present "hi"

λ> :present 123

λ> :present (5.2,"hi",1,'a')

λ> data X a = X a Int

λ> :present X 5 1
X 5 1

λ> :present S88.pack "hi"
PS (ForeignPtr GHC.Prim.Addr# (PlainPtr GHC.Prim.MutableByteArray#)) 0 2

λ> :present print
<a_0 -> GHC.Types.IO ()>

λ> :present print ()
IO (<GHC.Prim.State# GHC.Prim.RealWorld -> (GHC.Prim.State# GHC.Prim.RealWorld, a_0)>)

λ> :present undefined
_ :: t_0

λ> :present id
<a_0 -> a_0>

λ> :present [undefined]
[_ :: t_0]


You can write your own instances like this:

λ> data X = X Int
λ> :present X 5
X 5
λ> instance Present0 X where present0 = ("X",\(X x) -> IntegerPresentation "X" (show x))
λ> :present X 5