| definition: |
wEither :: (Eq a, Eq b) => WuiSpec a -> WuiSpec b -> WuiSpec (Either a b)
wEither (WuiSpec rendera showa cora reada) (WuiSpec renderb showb corb readb) =
WuiSpec (head, "?", const True) showEither corEither readEither
where
showEither (render,errmsg,legal) nocheck (Left va) =
let (hea,rta) = showa rendera nocheck va
in ((if nocheck || legal (Left va)
then render
else renderError render errmsg) [hea], altstate2state (1,rta))
showEither (render,errmsg,legal) nocheck (Right vb) =
let (heb,rtb) = showb renderb nocheck vb
in ((if nocheck || legal (Right vb)
then render
else renderError render errmsg) [heb], altstate2state (2,rtb))
corEither wparam vab = conditionOf wparam vab &&
either (cora rendera) (corb renderb) vab
readEither env s =
let (altindex,rab) = state2altstate s
in case altindex of
1 -> Left (reada env rab)
2 -> Right (readb env rab)
|
| demand: |
arguments 3 4 |
| deterministic: |
deterministic operation |
| documentation: |
--- WUI for union types. --- Here we provide only the implementation for Either types --- since other types with more alternatives can be easily reduced to this case. |
| failfree: |
<FAILING> |
| indeterministic: |
referentially transparent operation |
| infix: |
no fixity defined |
| iotype: |
{(_,_,{WuiSpec},{WuiSpec}) |-> {WuiSpec}}
|
| name: |
wEither |
| precedence: |
no precedence defined |
| result-values: |
{WuiSpec}
|
| signature: |
(Prelude.Eq a, Prelude.Eq b) => WuiSpec a -> WuiSpec b -> WuiSpec (Prelude.Either a b) |
| solution-complete: |
operation might suspend on free variables |
| terminating: |
yes |
| totally-defined: |
possibly non-reducible on same data term |