OrPatterns: A quasiquoter for or-patterns

A quasiquoter for or-patterns. It allows one additional form for patterns:

f [o| p1 | p2 | p3 |] = rhs

Above, p1, p2 and p3 are three arbitrary patterns that bind the same variables. These variables are available in the expression rhs. Nesting of or-patterns is not supported yet.

See also:

• http://hackage.haskell.org/package/first-class-patterns supports \/ (or). However, variables bound with those patterns are not named. This means:

g :: Either (x, y) (y, x) -> (x, y)
g [o| Left (x,y) | Right (y,x) |] = (x,y)

-- ends up slightly longer
g = elim $ left (pair var var) \/ right flipped ->> (,)
 where
  flipped = (\(a,b) -> (b,a)) --> pair var var

• http://hackage.haskell.org/trac/ghc/ticket/3919 is the feature request for or-patterns in ghc

Modules

[Index]

Downloads

• OrPatterns-0.1.tar.gz [browse] (Cabal source package)
• Package description (as included in the package)

Maintainer's Corner

Package maintainers

• AdamVogt

For package maintainers and hackage trustees

• edit package information

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