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exon: Customizable quasiquote interpolation

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Versions [RSS] 0.1.0.0, 0.1.1.0, 0.2.0.0, 0.2.0.1, 0.3.0.0, 0.4.0.0, 0.5.0.0, 1.0.0.0, 1.0.0.1, 1.0.0.2, 1.0.1.0, 1.1.0.0, 1.2.0.0, 1.3.0.0, 1.4.0.0, 1.5.0.0, 1.5.0.1, 1.6.0.0, 1.6.0.1, 1.6.0.2, 1.6.1.0, 1.6.1.1, 1.7.0.0, 1.7.1.0, 1.7.2.0 (info)
Change log changelog.md
Dependencies base (>=4.16.4.0 && <4.22), ghc (>=9.2.8 && <9.13), incipit-base (>=0.5.0.0 && <0.7), parsec (>=3.1.15.0 && <3.2), template-haskell (>=2.18.0.0 && <2.24) [details]
License BSD-2-Clause-Patent
Copyright 2025 Torsten Schmits
Author Torsten Schmits
Maintainer hackage@tryp.io
Category String
Home page https://github.com/tek/exon#readme
Bug tracker https://github.com/tek/exon/issues
Source repo head: git clone https://github.com/tek/exon
Uploaded by tek at 2025-03-15T14:51:39Z
Distributions LTSHaskell:1.7.2.0, NixOS:1.7.2.0, Stackage:1.7.2.0
Reverse Dependencies 15 direct, 6 indirect [details]
Downloads 2051 total (17 in the last 30 days)
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Status Docs uploaded by user
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Readme for exon-1.7.2.0

[back to package description]

This Haskell library provides string interpolation in quasiquotes, allowing you to build strings like this:

animal = "snake"
location = "a tree"
[exon|#{animal} in #{location}|]
-- "snake in a tree"

Each step of the process is customizable based on the result type of the quote, making it possible to construct strings for arbitrary types. For example, String -> String is the type used by showsPrec, which can be a bit of a hassle to write:

data Record =
  Record {
    number :: Int,
    maybeNumber :: Maybe Int,
    value :: Value
  }

instance Show Record where
  showsPrec d Record {..} =
    showParen (d > 10) [exon|Record #{showsPrec 11 number} #{showsPrec 11 maybeNumber} #{showsPrec 11 value}|]