GUI component interaction: Difference between revisions

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@@ Line 625: / Line 625: @@
     ran   <- button frm [text := "random", on command := (randReplace fld frm)]
     set frm [layout := margin 5 $ floatCentre $ column 2
             [centre $ widget fld, row 2 [widget inc, widget ran]]]
 increment :: Textual w => w -> IO ()
 increment field = do
     val <- get field text
-    if (not . null) val
+    when ((not . null) val) $ set field [text := show $ 1 + read val]
-    then set field [text := show $ 1 + read val]
-    else return ()
 checkKeys :: EventKey -> IO ()
@@ Line 642: / Line 640: @@
 randReplace field frame = do
     answer <- confirmDialog frame "Random" "Generate a random number?" True
+    when answer $ getStdRandom (randomR (1,100)) >>= \num ->
-    if answer
+                  set field [text := show (num :: Int)]</lang>
-    then getStdRandom (randomR (1,100)) >>= \num ->
-         set field [text := show (num :: Int)]
-    else return ()</lang>
 ==Icon and {{header|Unicon}}==