/
Helpers.purs
37 lines (31 loc) · 953 Bytes
/
Helpers.purs
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module Economics.Utility.VNM.Helpers where
import Prelude
import Data.List (List(..), (:))
import Data.Map (Map)
import Data.Map as Map
import Data.Maybe (Maybe(..))
import Data.NonEmpty.Indexed as Indexed
import Data.Tuple (Tuple(..))
import Data.Unfoldable as Unfoldable
import Partial.Unsafe (unsafeCrashWith)
unsafeFromJustBecause :: forall a. String -> Maybe a -> a
unsafeFromJustBecause _ (Just a) = a
unsafeFromJustBecause str Nothing = unsafeCrashWith str
pairCombos :: forall a. List a -> List (Tuple a a)
pairCombos l = do
ls <- tails l
case ls of
Nil -> Nil
Cons x ys -> do
y <- ys
pure $ Tuple x y
nonEmptyMap ::
forall k v.
Ord k
=> Map k v
-> Maybe (Indexed.NonEmpty Map k v)
nonEmptyMap m =
(\l -> (Tuple l.key l.value) Indexed.:| (l.key `Map.delete` m)) <$> Map.findMin m
tails :: forall a. List a -> List (List a)
tails Nil = Unfoldable.singleton Nil
tails as'@(Cons a as) = as' : tails as