Difference between revisions of "Talk:Compose"

Latest revision as of 10:12, 9 February 2007

Reading this page got me to write an arrow version of compose. Don't know if it should be included or not since it isn't a monadic solution.

composeArrow :: [a -> a] -> a -> a <br/>
composeArrow = foldr ((>>>) . arr) (arr id)

Or maybe this:

composeArrow :: [a -> a] -> a -> a
composeArrow = foldl ((>>>) . arr) returnA

The first version does not need the function composition, because the functions could be applied immediately. This leads to

compose = flip (foldl (flip id))

Shall I replace the first solution?

I would write:

compose = foldr (flip (.)) id

@@ Line 1: / Line 1: @@
 Reading this page got me to write an arrow version of compose. Don't know if it should be included or not since it isn't a monadic solution.<p/>
-<code>
+<haskell>
 composeArrow :: [a -> a] -> a -> a <br/>
 composeArrow = foldr ((>>>) . arr) (arr id)
-</code>
+</haskell>
 <br>Or maybe this:<br>
-<code>
+<haskell>
 composeArrow :: [a -> a] -> a -> a
 composeArrow = foldl ((>>>) . arr) returnA
-</code>
+</haskell>
+----
+The first version does not need the function composition, because the functions could be applied immediately.
+This leads to
+<haskell>
+compose = flip (foldl (flip id))
+</haskell>
+Shall I replace the first solution?
+----
+I would write:
+<haskell>
+compose = foldr (flip (.)) id
+</haskell>