Synnefo » snf-ganeti » ganeti-local

    , if'

    , select

-- *  Logical functions

-- Avoid syntactic sugar and enhance readability. These functions are proposed

-- by some for inclusion in the Prelude, and at the moment they are present

-- (with various definitions) in the utility-ht package. Some rationale and

-- discussion is available at <http://www.haskell.org/haskellwiki/If-then-else>

-- | \"if\" as a function, rather than as syntactic sugar.

if' :: Bool -- ^ condition

    -> a    -- ^ \"then\" result

    -> a    -- ^ \"else\" result

    -> a    -- ^ \"then\" or "else" result depending on the condition

if' True x _ = x

if' _    _ y = y

-- | Return the first result with a True condition, or the default otherwise.

select :: a            -- ^ default result

       -> [(Bool, a)]  -- ^ list of \"condition, result\"

       -> a            -- ^ first result which has a True condition, or default

select def = maybe def snd . find fst