Added Prelude/maybe

[simantics/platform.git] / bundles / org.simantics.scl.runtime / scl / Prelude.scl

diff --git a/bundles/org.simantics.scl.runtime/scl/Prelude.scl b/bundles/org.simantics.scl.runtime/scl/Prelude.scl
index cce9064090ca123545e387b711e7cab902e95680..03eabb66fb8ecd2ff7218fa5191db648350ee280 100644 (file)
--- a/bundles/org.simantics.scl.runtime/scl/Prelude.scl
+++ b/bundles/org.simantics.scl.runtime/scl/Prelude.scl
@@ -48,10 +48,6 @@ type FloatArray = Vector Float
 type DoubleArray = Vector Double
 
 importJava "java.util.Arrays" where
-    @private
-    @JavaName toString
-    showDoubleArray :: DoubleArray -> String
-    
     "Converts an array to a list."
     @JavaName asList    
     arrayToList :: Array a -> [a]
@@ -61,9 +57,6 @@ importJava "java.util.List" where
     @JavaName toArray
     listToArray :: [a] -> Array a
 
-instance Show DoubleArray where
-    show = showDoubleArray
-
 importJava "org.simantics.scl.runtime.Coercion" where
     "Converts a list of doubles to a double array."
     toDoubleArray :: [Double] -> DoubleArray
@@ -1173,10 +1166,12 @@ class IndexedSequence f where
 
 "Returns the first element of a sequence"
 @inline
+first :: [a] -> a
 first l = l!0
 
 "Returns the last element of a sequence"
 @inline
+last :: [a] -> a
 last l = l!(length l-1)
 
 instance IndexedSequence [] where
@@ -1295,8 +1290,12 @@ fromMaybe :: a -> Maybe a -> a
 fromMaybe default maybeValue = match maybeValue with
     Just v -> v
     _ -> default
-    
-    
+
+"`maybe def f v` returns `def` if `v=Nothing` and `f x` if `v=Just x`."
+maybe :: b -> (a -> <e> b) -> Maybe a -> <e> b
+maybe n _ Nothing  = n
+maybe _ f (Just x) = f x
+
 """
 Provides a default value if the first parameter is Nothing.
 The default value is evaluated only if needed. The function
@@ -1312,6 +1311,11 @@ orElse :: Maybe a -> (<e> a) -> <e> a
 orElse (Just x) _   = x
 orElse Nothing  def = def
 
+@inline
+orElseM :: Maybe a -> (<e> Maybe a) -> <e> Maybe a
+orElseM mx@(Just x) _   = mx
+orElseM Nothing     def = def
+
 /// Either ///
 
 """
@@ -1967,6 +1971,11 @@ importJava "org.simantics.scl.runtime.Lists" where
     """
     index :: [(a,b)] -> a -> Maybe b
     
+    """
+    Given a list of elements, the function produces its characteristic function.
+    """
+    indexSet :: [a] -> a -> Boolean
+    
     """
     Given a list of values and a function computing a key for each value, the function produces a function that finds a value
     effeciently for the given key.
@@ -1994,7 +2003,7 @@ importJava "org.simantics.scl.runtime.Lists" where
     unique :: [a] -> [a]
     
     "Like `unique`, but uses the given function for finding the key values used for uniqueness testing."
-    uniqueBy :: (a -> b) -> [a] -> [a]
+    uniqueBy :: (a -> <e> b) -> [a] -> <e> [a]
 
     "Works like `unique` but uses the given function for equality tests."
     uniqueWith :: (a -> a -> Boolean) -> [a] -> [a]
@@ -2055,6 +2064,7 @@ Transposes the rows and columns of its argument. For example,
     transpose [[1,2,3],[4,5,6]] == [[1,4],[2,5],[3,6]]
     transpose [[1,2],[3,4,5]] == [[1,3],[2,4],[5]]
 """
+transpose :: [[a]] -> [[a]]
 transpose xss = [[xs!i | xs <- xss, i < length xs]
                 | i <- [0..maximum [length xs | xs <- xss]-1]]
 
@@ -2290,16 +2300,6 @@ instance Show TypeRep where
         isSpecialType (TApply a _) = isSpecialType a
 */
 
-// ByteArray
-
-importJava "java.util.Arrays" where
-    @private
-    @JavaName toString
-    byteArrayToString :: ByteArray -> String
-
-instance Show ByteArray where
-    show = byteArrayToString
-
 // Type
 
 @private