ifcxt: put if statements within type constraints

[ bsd3, control, library ] [ Propose Tags ]

This package introduces the ifCxt function, which lets your write if statements that depend on a polymorphic variable's class instances. For example, we can make a version of show that can be called on any type:

cxtShow :: forall a. IfCxt (Show a) => a -> String
cxtShow a = ifCxt (Proxy::Proxy (Show a))
    (show a)
    "<<unshowable>>"

Running this function in ghci, we get:

>>> cxtShow (1 :: Int)
"1"
>>> cxtShow (id :: a -> a)
"<<unshowable>>"

See the project webpage http://github.com/mikeizbicki/ifcxt for more details.

Versions [faq] 0.1.0.0, 0.1.1
Dependencies base (==4.8.*), template-haskell (==2.10.*) [details]
License BSD-3-Clause
Author Mike Izbicki
Maintainer mike@izbicki.me
Category Control
Home page http://github.com/mikeizbicki/ifcxt
Source repo head: git clone http://github.com/mikeizbicki/ifcxt
Uploaded by MikeIzbicki at Wed Sep 2 22:47:01 UTC 2015
Distributions NixOS:0.1.1
Downloads 892 total (18 in the last 30 days)
Rating 2.25 (votes: 2) [estimated by rule of succession]
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Status Hackage Matrix CI
Docs available [build log]
Last success reported on 2015-09-29 [all 3 reports]

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