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Diffstat (limited to 'gemfeed/2010-04-09-standard-ml-and-haskell.html')
| -rw-r--r-- | gemfeed/2010-04-09-standard-ml-and-haskell.html | 22 |
1 files changed, 11 insertions, 11 deletions
diff --git a/gemfeed/2010-04-09-standard-ml-and-haskell.html b/gemfeed/2010-04-09-standard-ml-and-haskell.html index c1e26db2..e99e71dd 100644 --- a/gemfeed/2010-04-09-standard-ml-and-haskell.html +++ b/gemfeed/2010-04-09-standard-ml-and-haskell.html @@ -20,7 +20,7 @@ datatype ’a multi = EMPTY | ELEM of ’a | UNION of ’a multi * ’a multi -</pre> +</pre><br /> <p>Haskell:</p> <pre> data (Eq a) => Multi a @@ -28,7 +28,7 @@ data (Eq a) => Multi a | Elem a | Union (Multi a) (Multi a) deriving Show -</pre> +</pre><br /> <h2>Processing a multi</h2> <p>Standard ML:</p> <pre> @@ -38,7 +38,7 @@ fun number (EMPTY) _ = 0 fun test_number w = number (UNION (EMPTY, \ UNION (ELEM 4, UNION (ELEM 6, \ UNION (UNION (ELEM 4, ELEM 4), EMPTY))))) w -</pre> +</pre><br /> <p>Haskell:</p> <pre> number Empty _ = 0 @@ -46,7 +46,7 @@ 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 -</pre> +</pre><br /> <h2>Simplify function</h2> <p>Standard ML:</p> <pre> @@ -63,7 +63,7 @@ fun simplify (UNION (x,y)) = else UNION (x’, y’) end | simplify x = x -</pre> +</pre><br /> <p>Haskell:</p> <pre> simplify (Union x y) @@ -77,7 +77,7 @@ simplify (Union x y) x’ = simplify x y’ = simplify y simplify x = x -</pre> +</pre><br /> <h2>Delete all</h2> <p>Standard ML:</p> <pre> @@ -87,7 +87,7 @@ fun delete_all m w = | delete_all’ x = x in simplify (delete_all’ m) end -</pre> +</pre><br /> <p>Haskell:</p> <pre> delete_all m w = simplify (delete_all’ m) @@ -95,7 +95,7 @@ delete_all m w = simplify (delete_all’ m) 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 -</pre> +</pre><br /> <h2>Delete one</h2> <p>Standard ML:</p> <pre> @@ -114,7 +114,7 @@ fun delete_one m w = val (m’, _) = delete_one’ m in simplify m’ end -</pre> +</pre><br /> <p>Haskell:</p> <pre> delete_one m w = do @@ -130,7 +130,7 @@ delete_one m w = do delete_one’ (Elem x) = if x == w then (Empty, True) else (Elem x, False) delete_one’ x = (x, False) -</pre> +</pre><br /> <h2>Higher-order functions</h2> <p>The first line is always the SML code, the second line the Haskell variant:</p> <pre> @@ -145,7 +145,7 @@ my_map f l = foldr (make_map_fn f) [] l fun my_filter f l = foldr (make_filter_fn f) [] l my_filter f l = foldr (make_filter_fn f) [] l -</pre> +</pre><br /> <p>E-Mail me your comments to paul at buetow dot org!</p> <a class="textlink" href="../">Go back to the main site</a><br /> <p class="footer"> |