X-Git-Url: https://gerrit.simantics.org/r/gitweb?p=simantics%2Fplatform.git;a=blobdiff_plain;f=bundles%2Forg.simantics.scl.runtime%2Fscl%2FPrelude.scl;h=c04cc8625aa0be2bceb1ab372f8f9fe5a7eca5c4;hp=77e62c8582215cb6a4afcd3c4d65e26275bac0f1;hb=46ea0d713406fbd0a0d8a8e5f41b7fb8ea7001c3;hpb=de191b2614db104b4cd02d53a05c8896b10c4c90

diff --git a/bundles/org.simantics.scl.runtime/scl/Prelude.scl b/bundles/org.simantics.scl.runtime/scl/Prelude.scl
index 77e62c858..c04cc8625 100644
--- a/bundles/org.simantics.scl.runtime/scl/Prelude.scl
+++ b/bundles/org.simantics.scl.runtime/scl/Prelude.scl
@@ -74,7 +74,7 @@ infixl 5  (\\), (<<), (<+)
 infix  4  (!=), (<), (<=), (>=), (>)
 infixr 3  (&&), (&<&)
 infixr 2  (||), orElse, morelse
-infixr 1  (>>=), (>>), (:=)
+infixr 1  (>>=), (>>), (:=), (>=>)
 infixr 1  ($)
 infixl 1  catch
 
@@ -921,6 +921,10 @@ Sequentially compose two actions, discarding any value produced by the first, li
 (>>) :: Monad m => m a -> m b -> m b
 a >> b = a >>= (\_ -> b)
 
+"Left-to-right Kleisli composition of monads."
+(>=>) :: Monad m => (a -> m b) -> (b -> m c) -> (a -> m c)
+(f >=> g) x = (f x) >>= g 
+
 "While loop. `while cond body` executes the `body` while the `cond` is true." 
 @inline
 while :: (<e> Boolean) -> (<e> a) -> <e> ()
@@ -1077,13 +1081,29 @@ replicate n v = build (\empty cons ->
 
 /// FunctorM ///
 
-class (Functor f) => FunctorM f where
+class (FunctorE f) => FunctorM f where
     "`mapM f` is equivalent to `sequence . map f`."
-    mapM :: Monad m => (a -> m b) -> f a -> m (f b)
+    mapM :: Monad m => (a -> <e> m b) -> f a -> <e> m (f b)
     "Evaluate each action in the sequence from left to right, and collect the results."
     sequence :: Monad m => f (m a) -> m (f a) 
-    mapM f l = sequence (fmap f l)
+    mapM f l = sequence (map f l)
+
+/// MonadE ///
+
+class (FunctorE m, Monad m) => MonadE m where
+    bindE :: m a -> (a -> <e> m b) -> <e> m b
+
+instance MonadE Maybe where
+    bindE Nothing  _ = Nothing
+    bindE (Just v) f = f v
+    
+instance MonadE (Either a) where
+    bindE (Left v)  _ = Left v
+    bindE (Right v) f = f v
 
+instance MonadE [] where
+    bindE l f = concatMap f l
+    
 /// Category ///
 
 "Identity function."
@@ -1142,6 +1162,14 @@ class IndexedSequence f where
     "`seq ! i` returns the `i`th element of the sequence `seq`. Indexing starts from zero."
     (!) :: f a -> Integer -> a
 
+"Returns the first element of a sequence"
+@inline
+first l = l!0
+
+"Returns the last element of a sequence"
+@inline
+last l = l!(length l-1)
+
 instance IndexedSequence [] where
     (!) = getList
 
@@ -1910,14 +1938,51 @@ importJava "org.simantics.scl.runtime.Lists" where
     
     "Sorts the list using the given comparator."
     sortWith :: (a -> a -> <e> Integer) -> [a] -> <e> [a]
+    
+    """
+    Given a list of key-value pairs, the function produces a function that finds a value
+    efficiently for the given key.
+    """
+    index :: [(a,b)] -> a -> Maybe b
+    
+    """
+    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.
+    """
+    indexBy ::  (a -> <e> b) -> [a] -> <e> (b -> Maybe a)
+    
     "Works like `index` but uses the given functions as hash codes and equality."
     indexWith :: (a -> Integer) -> (a -> a -> Boolean) -> [(a,b)] -> a -> Maybe b
+    
+    "Groups a list values by a key computed by the given function."
+    groupBy :: (a -> <e> b) -> [a] -> <e> [(b, [a])]
+    
+    "Groups a list of key-value pairs by the keys."
+    group :: [(a,b)] -> [(a, [b])]
+
+    "Composition of index and groupBy."
+    indexGroupBy :: (a -> <e> b) -> [a] -> <e> (b -> [a])
+    
+    "Composition of index and group."
+    indexGroup :: [(a,b)] -> a -> [b]
+    
     groupWith :: (b -> Integer) -> (b -> b -> Boolean) -> (a -> <e> b) -> (a -> <e> c) -> [a] -> <e> [(b, [c])]
+    
+    "Removes duplicates (all but the first occurrence) from the list but otherwise preserves the order of the elements."
+    unique :: [a] -> [a]
+    
+    "Like `unique`, but uses the given function for finding the key values used for uniqueness testing."
+    uniqueBy :: (a -> b) -> [a] -> [a]
+
     "Works like `unique` but uses the given function for equality tests."
     uniqueWith :: (a -> a -> Boolean) -> [a] -> [a]
+    
     "Works like `\\\\` but uses the given function for equality tests."
     deleteAllBy :: (a -> a -> Boolean) -> [a] -> [a] -> [a]
     
+    @private
+    listDifference :: [a] -> [a] -> [a]
+    
     //range :: Integer -> Integer -> [Integer]
     
     //build :: (forall a. a -> (a -> b -> <e> a) -> <e> a) -> <e> [b]
@@ -1938,6 +2003,16 @@ elemMaybe el m = match m with
     Just el2 -> el == el2
     Nothing -> False
 
+"`elemIndex el lst` returns the index of the first element in the given list `lst` which is equal (by ==) to the query element, or Nothing if there is no such element."
+elemIndex :: a -> [a] -> Maybe Integer
+elemIndex el l = loop 0
+  where
+    len = length l
+    loop i | i < len = if el == l!i
+                       then Just i
+                       else loop (i+1)
+           | otherwise = Nothing
+
 """
 Computes a list that contains only elements that belongs to both input lists.
 """
@@ -2042,42 +2117,9 @@ sortBy f l = sortWith (\x y -> compare (f x) (f y)) l
 // This is faster if f is slow, but will generate more auxiliary structures
 //sortBy f l = map snd (sortWith (\(x,_) (y,_) -> compare x y) [(f x, x) | x <- l])
 
-"""
-Given a list of key-value pairs, the function produces a function that finds a value
-efficiently for the given key.
-"""
-index :: [(a,b)] -> a -> Maybe b
-index = indexWith hashCode (==)
-
-"""
-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.
-"""
-indexBy ::  (a -> b) -> [a] -> b -> Maybe a
-indexBy f l = index [(f x, x) | x <- l]
-
-"Groups a list values by a key computed by the given function."
-groupBy :: (a -> <e> b) -> [a] -> <e> [(b, [a])]
-groupBy f l = groupWith hashCode (==) f id l
-
-"Groups a list of key-value pairs by the keys."
-group :: [(a,b)] -> [(a, [b])]
-group = groupWith hashCode (==) fst snd
-
-"Removes duplicates (all but the first occurrence) from the list but otherwise preserves the order of the elements."
-unique ::  [a] -> [a]
-unique = uniqueWith (==)
-
-"Like `unique`, but uses the given function for finding the key values used for uniqueness testing."
-uniqueBy :: (a -> b) -> [a] -> [a]
-uniqueBy f = uniqueWith (\a b -> f a == f b)
-
-//sortAndUniqueBy :: Ord b => (a -> b) -> [a] -> [a]
-//sortAndUniqueBy f = map snd . uniqueWith (\a b -> fst a == fst b) . sortBy fst . map (\x -> (f x, x))
-
 "`a \\\\ b` removes all elements of `b` from the list `a`."
 (\\) :: [a] -> [a] -> [a]
-(\\) = deleteAllBy (==)
+(\\) = listDifference
 
 /// Dynamic ///