Difference between revisions of "Yhc/Javascript/Programmers guide/EchoCPS2 demo source"
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| − | <haskell> |
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| − | -- A program similar to the Echo program, written |
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| − | -- without monads as the first step to Fudgets adoption. |
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| − | -- The program also demonstrates use of the DOM Level2 framework |
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| − | -- also implemented in CPS style. |
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| − | |||
| − | module EchoCPS2 where |
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| − | |||
| − | -- This module contains useful functions to access properties of underlying |
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| − | -- Javascript objects in the type-agnostic manner: proceed with caution! |
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| − | import UnsafeJS |
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| − | |||
| − | -- This module contains functions to wrap expressions in CPS style |
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| − | import CPS |
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| − | |||
| − | -- This module contains Roman-Decimal conversion funcitons |
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| − | import Roman |
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| − | |||
| − | -- The modules under DOM are autogenerated from IDL |
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| − | -- The modules under CDOM are utilities to simplify the use of DOM facilities |
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| − | import DOM.Level2.Dom |
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| − | import DOM.Level2.Html2 |
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| − | import CDOM.Level2.DomUtils |
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| − | import CDOM.Level2.Events |
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| − | import DOM.Level2.Events |
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| − | import DOM.Level2.Document |
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| − | import DOM.Level2.HTMLElement |
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| − | import DOM.Level2.HTMLDivElement |
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| − | import DOM.Level2.HTMLInputElement |
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| − | import DOM.Level2.KeyEvent |
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| − | |||
| − | -- This module contains functions to obtain timestamps |
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| − | import Debug.Profiling |
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| − | |||
| − | -- Line-mode output: create a <div> element, place a text in it, |
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| − | -- append to the parent element (document body). The mbb argument |
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| − | -- specifies whether the text will be inserted before a specific |
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| − | -- element (Just) or just appended to the end of the document (Nothing). |
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| − | -- The s argument is the string to output, and the c argument is |
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| − | -- the continuation. |
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| − | |||
| − | putLine s mbb c = getHTMLDocument $ \doc -> |
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| − | documentBody doc $ \body -> |
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| − | mkDiv doc $ \dv -> |
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| − | mkText doc s $ \tx -> |
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| − | addChild tx dv $ \ch -> |
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| − | let iac = case mbb of |
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| − | Nothing -> addChild dv |
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| − | Just b -> insertChild b dv |
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| − | in iac body $ \ct -> |
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| − | c ct |
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| − | |||
| − | |||
| − | main = getHTMLDocument $ \doc -> |
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| − | documentBody doc $ \body -> |
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| − | putLine ("*** Echo Benchmark ***") nodeNothing $ \_ -> |
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| − | mkInput doc $ \inp -> |
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| − | addChild inp body $ \_ -> |
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| − | set'id "input-echo" inp $ \_ -> |
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| − | setEventHandler "keypress" (inkey inp) inp $ \_ -> |
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| − | |||
| − | -- The setEventHandler function still uses the "on-" element attributes, |
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| − | -- but given better event type information is contained in the DOM Level2 |
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| − | -- definitions, the handler type signature may be set. |
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| − | |||
| − | -- The setEventHandler itself has type: |
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| − | -- setEventHandler :: (CElement zz, CEvent a) => String -> (a -> Bool) -> zz -> CPS c zz |
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| − | |||
| − | focus inp $ id |
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| − | |||
| − | romdec :: String -> (String, String) |
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| − | |||
| − | romdec v = |
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| − | let rom = (catchJS ((show . fromRoman) v) (\_ -> "")) |
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| − | dec = (catchJS ((toRoman . read) v) (\_ -> "")) |
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| − | in (rom, dec) |
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| − | |||
| − | -- The "onkeypress" handler: it does all the job. Note the o argument: |
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| − | -- it holds reference to the element a handler is attached to. This forms |
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| − | -- a closure (which may not be very much desired for some browsers), but |
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| − | -- makes it extremely easy to distinguish between elements that cause |
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| − | -- the handler to fire. The e argument is expected to be of the TKeyEvent |
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| − | -- type (defined in DOM IDL). |
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| − | |||
| − | inkey :: THTMLInputElement -> TKeyEvent -> Bool |
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| − | |||
| − | -- Now it is possible to refer to event object methods and attributes |
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| − | -- in type safe manner instead of unsafe getting attributes by name. |
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| − | -- The KeyEvent interface defines the cDOM_VK_ENTER constant for the |
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| − | -- "Enter" key. |
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| − | |||
| − | inkey o e = get'keyCode e $ \kci -> |
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| − | if kci == cDOM_VK_ENTER |
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| − | then |
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| − | get'value o $ \v -> |
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| − | if length v > 0 |
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| − | then |
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| − | getTimeStamp $ \t1 -> |
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| − | toCPE (romdec v) $ \(rom, dec) -> |
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| − | rom `seq` dec `seq` getTimeStamp $ \t2 -> |
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| − | putLine (v ++ " " ++ rom ++ " " ++ dec ++ " " ++ show (t2 - t1) ++ " ms") |
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| − | (Just o) $ \_ -> |
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| − | set'value "" o $ \_ -> |
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| − | True |
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| − | else |
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| − | True |
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| − | else True |
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| − | </haskell> |
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