mirror of
https://github.com/unisonweb/unison.git
synced 2024-09-11 10:35:57 +03:00
1.9 KiB
1.9 KiB
scratch/main> builtins.merge
id x = x
structural ability Stream a where
emit : a -> ()
Stream.foldl : (x ->{g} a ->{g} x) -> x -> '{g, Stream a} r -> '{g} x
Stream.foldl f z str _ =
h acc = cases
{ emit x -> k } -> handle !k with h (f acc x)
{ _ } -> acc
handle !str with h z
Stream.range : Nat -> Nat -> '{Stream Nat} ()
Stream.range m n = do
f : Nat ->{Stream Nat} ()
f k = if k < n then emit k ; f (k+1) else ()
f m
unique type Fold' g a b x = Fold' (x -> {g} a -> {g} x) x (x -> {g} b)
unique type Fold g a b = Fold (∀ g2 r. (∀ x. Fold' g a b x -> {g2} r) -> {g2} r)
Fold.fromFold' : Fold' g a b x -> Fold g a b
Fold.fromFold' fold = Fold.Fold (f -> f fold)
Fold.mkFold : (t -> {g} a -> {g} t) -> t -> (t -> {g} b) -> Fold g a b
Fold.mkFold step init extract =
Fold.fromFold' (Fold'.Fold' step init extract)
folds.all : (a -> {g} Boolean) -> Fold g a Boolean
folds.all predicate =
Fold.mkFold (b -> a -> b && (predicate a)) true id
Fold.Stream.fold : Fold g a b -> '{g, Stream a} r -> '{g} b
Fold.Stream.fold =
run: Fold' g a b x -> '{g, Stream a} r -> '{g} b
run =
cases Fold'.Fold' step init extract ->
stream -> _ -> extract !(foldl step init stream)
cases
Fold f -> stream -> f (f' -> run f' stream)
> folds.all.tests.stream =
pred = n -> (Nat.gt n 2)
res : 'Boolean
res = Fold.Stream.fold (folds.all pred) (Stream.range 1 5)
!res Universal.== false
Tests some capabilities for catching runtime exceptions.
catcher : '{IO} () ->{IO} Result
catcher act =
handle tryEval act with cases
{ raise _ -> _ } -> Ok "caught"
{ _ } -> Fail "nothing to catch"
tests _ =
[ catcher do
_ = 1/0
()
, catcher '(bug "testing")
, handle tryEval (do 1+1) with cases
{ raise _ -> _ } -> Fail "1+1 failed"
{ 2 } -> Ok "got the right answer"
{ _ } -> Fail "got the wrong answer"
]
scratch/main> add
scratch/main> io.test tests