haskell - How can I create a value with a specific TypeRep -


using data.typeable, can reify type of value -

typeof :: typeable => -> typerep

however, given typerep, there seems no way "set" value type.

for example -

maybeinttype :: typerep maybeinttype = typeof (just 100 :: maybe int)

but how use maybeinttype create (nothing :: maybe int)?


Comments

Post a Comment

Popular posts from this blog

resizing Telegram inline keyboard -

telegram's inline keyboard great feature lots of different use cases. inline buttons added list of items this: inline_keyboard = [[inlinekeyboardbutton(text="button", callback_data="button"), inlinekeyboardbutton(text="reset",callback_data="reset")]] inline_keyboard_markup = inlinekeyboardmarkup(inline_keyboard) update.message.reply_text("hi", reply_markup=inline_keyboard_markup) the above code adds 2 buttons each half width of chat screen. i know the normal keyboard button there resize_keyboard parameter somehow can used. my question is there way resize inline buttons ? example make full width or quarter width. unfortunately, can't now. :( you can suggest @botsupport , might add feature next version.
Read more

command line - How can a Python program background itself? -

consider following python command-line program. doesn't work because incomplete, think illustrates problem: #!/usr/bin/python3 import multiprocessing pool = multiprocessing.pool() task in expensive_iterator_with_user_interaction(): pool.call_async(expensive_computation, (task,)) pool.close() print("dear user, may press ctrl-z , bg script.") pool.join() thus, problem scripts needs user input while it's launching expensive parallel processes. there moment when user interaction not needed anymore. then, ask user background process shell actions. however, can achieved program itself? (side note: core of problem entanglement of user input firing “expensive computations”. therefore, cannot separate both in 2 scripts, , letting 1 spawning other daemon.) the command screen may you. use screen -l create new session , run application. after inputting data, can press " ctrl-a " , press " d " on keyboard detach session. now...
Read more

android - How to prevent keyboard from closing when bottom dialog is open? -

Image
is there way not close keyboard, show dialog insted of keyboard(over it). after dialog closed need continiue typing without opening keyboard again? this dialog simple child of bottomdialogsheet: public class bottompage extends bottomsheetdialog { public bottompage(@nonnull context context) { super(context); view v = view.inflate(context, r.layout.layout_bottom_sheet, null); setcontentview(v); } } i've got implementation popup window covers keyboard other layout, there same problem when first opent popup , after press edit text show keyboard - popup hides, keyboard shows. how can prevent it, , let keyboard show without popup hiding? you can't simple. have window , keybord height that. look @ library , make own: https://github.com/ankushsachdeva/emojicon
Read more