| definition: |
matchHead :: Queue a -> Maybe (a, Queue a) matchHead (S _ [] _ [] ) = Nothing matchHead (S _ [] _ [x] ) = Just (x, empty) matchHead (S _ [] _ (_:_:_)) = error $ "Data.Queue.matchHead: illegal queue" matchHead (S lenf (x:xs) lenr r ) = Just (x, deqReverse (check lenr r (lenf - 1) xs)) |
| demand: |
argument 1 |
| deterministic: |
deterministic operation |
| documentation: |
--- Matches the front of a queue. --- `matchHead q` is equivalent to --- `if isEmpty q then Nothing else Just (deqHead q, deqTail q)` --- but more efficient. |
| failfree: |
_ |
| indeterministic: |
referentially transparent operation |
| infix: |
no fixity defined |
| iotype: |
{({S}) |-> _}
|
| name: |
matchHead |
| precedence: |
no precedence defined |
| result-values: |
_ |
| signature: |
Queue a -> Prelude.Maybe (a, Queue a) |
| solution-complete: |
operation might suspend on free variables |
| terminating: |
possibly non-terminating |
| totally-defined: |
possibly non-reducible on same data term |