Ivory.Stdlib.Control

Documentation

ifte :: (IvoryStore a, IvoryZero (Stored a), GetAlloc eff ~ Scope s) => IBool -> Ivory eff a -> Ivory eff a -> Ivory eff a

when :: IBool -> Ivory eff () -> Ivory eff ()

unless :: IBool -> Ivory eff () -> Ivory eff ()

cond_ :: [Cond eff ()] -> Ivory eff ()

A multi-way if. This is useful for avoiding an explosion of nesting and parentheses in complex conditionals.

Instead of writing nested chains of ifs:

ifte_ (x >? 100)
  (store result 10)
  (ifte_ (x >? 50)
    (store result 5)
    (ifte_ (x >? 0)
      (store result 1)
      (store result 0)))

You can write:

cond_
  [ x >? 100 ==> store result 10
  , x >? 50  ==> store result 5
  , x >? 0   ==> store result 1
  , true     ==> store result 0
  ]

Note that "==>" is non-associative and has precedence 0, so you will need parentheses to call functions with "$" on the left-hand side:

cond_ [ (f $ g x) ==> y ]

rather than:

cond_ [ f $ g x ==> y ]

cond :: (IvoryStore a, IvoryZero (Stored a), GetAlloc eff ~ Scope s) => [Cond eff a] -> Ivory eff a

(==>) :: IBool -> Ivory eff a -> Cond eff a infix 0

data Cond eff a