From 8a78337ea4dcb0b154bd1c754218ca01c8f9015d Mon Sep 17 00:00:00 2001 From: Paul Buetow Date: Sun, 8 Mar 2026 18:17:20 +0200 Subject: Update content for html --- gemfeed/2010-04-09-standard-ml-and-haskell.html | 184 ++++++++++++------------ 1 file changed, 95 insertions(+), 89 deletions(-) (limited to 'gemfeed/2010-04-09-standard-ml-and-haskell.html') diff --git a/gemfeed/2010-04-09-standard-ml-and-haskell.html b/gemfeed/2010-04-09-standard-ml-and-haskell.html index 7fc14e02..52440e1a 100644 --- a/gemfeed/2010-04-09-standard-ml-and-haskell.html +++ b/gemfeed/2010-04-09-standard-ml-and-haskell.html @@ -2,12 +2,17 @@ + Standard ML and Haskell - + +
+
+
+

Home | Markdown | Gemini

@@ -40,10 +45,10 @@ by Lorenzo Bettini http://www.lorenzobettini.it http://www.gnu.org/software/src-highlite --> -
datatype ’a multi
-	= EMPTY
-	| ELEM of ’a
-	| UNION of ’a multi * ’a multi
+
datatype ’a multi
+	= EMPTY
+	| ELEM of ’a
+	| UNION of ’a multi * ’a multi
 

 

 Haskell:

@@ -52,11 +57,11 @@ http://www.gnu.org/software/src-highlite -->
 by Lorenzo Bettini
 http://www.lorenzobettini.it
 http://www.gnu.org/software/src-highlite -->
-
data (Eq a) => Multi a
-    = Empty
-    | Elem a
-    | Union (Multi a) (Multi a)
-    deriving Show
+
data (Eq a) => Multi a
+    = Empty
+    | Elem a
+    | Union (Multi a) (Multi a)
+    deriving Show
 

 

 
Processing a multi


@@ -67,12 +72,12 @@ http://www.gnu.org/software/src-highlite -->
 by Lorenzo Bettini
 http://www.lorenzobettini.it
 http://www.gnu.org/software/src-highlite -->
-
fun number (EMPTY) _ = 0
-	| number (ELEM x) w = if x = w then 1 else 0
-	| number (UNION (x,y)) w = (number x w) + (number y w)
-fun test_number w = number (UNION (EMPTY, \
-    UNION (ELEM 4, UNION (ELEM 6, \
-    UNION (UNION (ELEM 4, ELEM 4), EMPTY))))) w 
+
fun number (EMPTY) _ = 0
+	| number (ELEM x) w = if x = w then 1 else 0
+	| number (UNION (x,y)) w = (number x w) + (number y w)
+fun test_number w = number (UNION (EMPTY, \
+    UNION (ELEM 4, UNION (ELEM 6, \
+    UNION (UNION (ELEM 4, ELEM 4), EMPTY))))) w 
 

 

 Haskell:

@@ -81,11 +86,11 @@ http://www.gnu.org/software/src-highlite -->
 by Lorenzo Bettini
 http://www.lorenzobettini.it
 http://www.gnu.org/software/src-highlite -->
-
number Empty _ = 0
-number (Elem x) w = if x == w then 1 else 0
-test_number w = number (Union Empty \
-    (Union (Elem 4) (Union (Elem 6) \
-    (Union (Union (Elem 4) (Elem 4)) Empty)))) w
+
number Empty _ = 0
+number (Elem x) w = if x == w then 1 else 0
+test_number w = number (Union Empty \
+    (Union (Elem 4) (Union (Elem 6) \
+    (Union (Union (Elem 4) (Elem 4)) Empty)))) w
 

 

 
Simplify function


@@ -96,19 +101,19 @@ test_number w = number (Union 
-
fun simplify (UNION (x,y)) =
-    let fun is_empty (EMPTY) = true | is_empty _ = false
-        val x’ = simplify x
-        val y’ = simplify y
-    in if (is_empty x’) andalso (is_empty y’)
-            then EMPTY
-       else if (is_empty x’)
-            then y’
-       else if (is_empty y’)
-            then x’
-       else UNION (x’, y’)
-    end
-  | simplify x = x
+
fun simplify (UNION (x,y)) =
+    let fun is_empty (EMPTY) = true | is_empty _ = false
+        val x’ = simplify x
+        val y’ = simplify y
+    in if (is_empty x’) andalso (is_empty y’)
+            then EMPTY
+       else if (is_empty x’)
+            then y’
+       else if (is_empty y’)
+            then x’
+       else UNION (x’, y’)
+    end
+  | simplify x = x
 

 

 Haskell:

@@ -117,17 +122,17 @@ http://www.gnu.org/software/src-highlite -->
 by Lorenzo Bettini
 http://www.lorenzobettini.it
 http://www.gnu.org/software/src-highlite -->
-
simplify (Union x y)
-    | (isEmpty x’) && (isEmpty y’) = Empty
-    | isEmpty x’ = y’
-    | isEmpty y’ = x’
-    | otherwise = Union x’ y’
-    where
-        isEmpty Empty = True
-        isEmpty _ = False
-        x’ = simplify x
-        y’ = simplify y
-simplify x = x
+
simplify (Union x y)
+    | (isEmpty x’) && (isEmpty y’) = Empty
+    | isEmpty x’ = y’
+    | isEmpty y’ = x’
+    | otherwise = Union x’ y’
+    where
+        isEmpty Empty = True
+        isEmpty _ = False
+        x’ = simplify x
+        y’ = simplify y
+simplify x = x
 

 

 
Delete all


@@ -138,12 +143,12 @@ simplify x = x
 by Lorenzo Bettini
 http://www.lorenzobettini.it
 http://www.gnu.org/software/src-highlite -->
-
fun delete_all m w =
-    let fun delete_all’ (ELEM x) = if x = w then EMPTY else ELEM x
-          | delete_all’ (UNION (x,y)) = UNION (delete_all’ x, delete_all’ y)
-          | delete_all’ x = x
-    in simplify (delete_all’ m)
-    end
+
fun delete_all m w =
+    let fun delete_all’ (ELEM x) = if x = w then EMPTY else ELEM x
+          | delete_all’ (UNION (x,y)) = UNION (delete_all’ x, delete_all’ y)
+          | delete_all’ x = x
+    in simplify (delete_all’ m)
+    end
 

 

 Haskell:

@@ -152,11 +157,11 @@ http://www.gnu.org/software/src-highlite -->
 by Lorenzo Bettini
 http://www.lorenzobettini.it
 http://www.gnu.org/software/src-highlite -->
-
delete_all m w = simplify (delete_all’ m)
-    where
-        delete_all’ (Elem x) = if x == w then Empty else Elem x
-        delete_all’ (Union x y) = Union (delete_all’ x) (delete_all’ y)
-        delete_all’ x = x
+
delete_all m w = simplify (delete_all’ m)
+    where
+        delete_all’ (Elem x) = if x == w then Empty else Elem x
+        delete_all’ (Union x y) = Union (delete_all’ x) (delete_all’ y)
+        delete_all’ x = x
 

 

 
Delete one


@@ -167,21 +172,21 @@ http://www.gnu.org/software/src-highlite -->
 by Lorenzo Bettini
 http://www.lorenzobettini.it
 http://www.gnu.org/software/src-highlite -->
-
fun delete_one m w =
-    let fun delete_one’ (UNION (x,y)) =
-            let val (x’, deleted) = delete_one’ x
-                in if deleted
-                   then (UNION (x’, y), deleted)
-                   else let val (y’, deleted) = delete_one’ y
-                       in (UNION (x, y’), deleted)
-                   end
-                end
-          | delete_one’ (ELEM x) =
-            if x = w then (EMPTY, true) else (ELEM x, false)
-          | delete_one’ x = (x, false)
-            val (m’, _) = delete_one’ m
-        in simplify m’
-    end
+
fun delete_one m w =
+    let fun delete_one’ (UNION (x,y)) =
+            let val (x’, deleted) = delete_one’ x
+                in if deleted
+                   then (UNION (x’, y), deleted)
+                   else let val (y’, deleted) = delete_one’ y
+                       in (UNION (x, y’), deleted)
+                   end
+                end
+          | delete_one’ (ELEM x) =
+            if x = w then (EMPTY, true) else (ELEM x, false)
+          | delete_one’ x = (x, false)
+            val (m’, _) = delete_one’ m
+        in simplify m’
+    end
 

 

 Haskell:

@@ -190,19 +195,19 @@ http://www.gnu.org/software/src-highlite -->
 by Lorenzo Bettini
 http://www.lorenzobettini.it
 http://www.gnu.org/software/src-highlite -->
-
delete_one m w = do
-    let (m’, _) = delete_one’ m
-    simplify m’
-    where
-        delete_one’ (Union x y) =
-            let (x’, deleted) = delete_one’ x
-            in if deleted
-                then (Union x’ y, deleted)
-                else let (y’, deleted) = delete_one’ y
-                    in (Union x y’, deleted)
-        delete_one’ (Elem x) =
-            if x == w then (Empty, True) else (Elem x, False)
-        delete_one’ x = (x, False)
+
delete_one m w = do
+    let (m’, _) = delete_one’ m
+    simplify m’
+    where
+        delete_one’ (Union x y) =
+            let (x’, deleted) = delete_one’ x
+            in if deleted
+                then (Union x’ y, deleted)
+                else let (y’, deleted) = delete_one’ y
+                    in (Union x y’, deleted)
+        delete_one’ (Elem x) =
+            if x == w then (Empty, True) else (Elem x, False)
+        delete_one’ x = (x, False)
 

 

 
Higher-order functions


@@ -227,11 +232,12 @@ my_filter f l = foldr (make_filter_fn f) [] l
 

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