| definition: |
wMaybe :: Eq a => WuiSpec Bool -> WuiSpec a -> a -> WuiSpec (Maybe a)
wMaybe (WuiSpec paramb showb _ readb) (WuiSpec parama showa cora reada) def =
WuiSpec
(renderTuple, tupleError, const True)
(\ (render,errmsg,legal) nocheck mbs ->
let (heb,rtb) = showb paramb nocheck (mbs/=Nothing)
(hea,rta) = showa parama nocheck (maybe def id mbs)
in ((if nocheck || legal mbs
then render
else renderError render errmsg) [heb,hea],
states2state [rtb,rta]))
(\wparams mbv -> conditionOf wparams mbv &&
maybe True (\v -> cora parama v) mbv)
(\env s ->
let [rb,ra] = state2states s
vb = readb env rb
va = reada env ra
in if vb then Just va else Nothing)
|
| demand: |
arguments 2 3 |
| deterministic: |
deterministic operation |
| documentation: |
--- WUI for Maybe values. It is constructed from a WUI for --- Booleans and a WUI for the potential values. Nothing corresponds --- to a selection of False in the Boolean WUI. --- The value WUI is shown after the Boolean WUI. --- @param wspecb - a WUI specification for Boolean values --- @param wspeca - a WUI specification for the type of potential values --- @param def - a default value that is used if the current value is Nothing |
| failfree: |
<FAILING> |
| indeterministic: |
referentially transparent operation |
| infix: |
no fixity defined |
| iotype: |
{(_,{WuiSpec},{WuiSpec},_) |-> {WuiSpec}}
|
| name: |
wMaybe |
| precedence: |
no precedence defined |
| result-values: |
{WuiSpec}
|
| signature: |
Prelude.Eq a => WuiSpec Prelude.Bool -> WuiSpec a -> a -> WuiSpec (Prelude.Maybe a) |
| solution-complete: |
operation might suspend on free variables |
| terminating: |
possibly non-terminating |
| totally-defined: |
possibly non-reducible on same data term |