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a monad constraint for "workflow effects", (just like MonadState is a monad constraint for "state effects") can use in any monad transformer stack that handles them.

a platform-agnostic free monad, which can be executed by platform-specific bindings.

church-encoded

the "Workflow Functor".

relates a Haskell type with a Objective-C type:

• Objective-C defines typedef unsigned short uint16_t;
• line 34 of /System/Library/Frameworks/ApplicationServices.framework/Versions/A/Frameworks/CoreGraphics.framework/Versions/A/Headers/CGRemoteOperation.h defines typedef uint16_t CGKeyCode;

relates a Haskell type with a Objective-C type:

• Objective-C defines typedef unsigned long long uint64_t;
• line 98 of /System/Library/Frameworks/ApplicationServices.framework/Versions/A/Frameworks/CoreGraphics.framework/Versions/A/Headers/CGEventTypes.h defines typedef uint64_t CGEventFlags;

an (unordered, no-duplicates) sequence of key chords make up a keyboard shortcut

pattern KeyChord ms k = (ms,k)

pattern NoMod k = ([],k)

appends a modifier

modifier keys are keys that can be "held".

the escape key is "pressed", not "held", it seems. (possibly explains its behavior in your terminal emulator?)

alt is OptionModifier.

all the keys on a standard Apple keyboard.

>>> int2keypress -12
[([],MinusKey),([],OneKey),([],TwoKey)]

a (base ten) digit is a number between zero and nine inclusive.

>>> digit2keypress 2
([],TwoKey)

>>> digit2keypress -2
Nothing

>>> digit2keypress 12
Nothing

the keypress that would insert the character into the application.

>>> char2keypress '@' :: Maybe KeyChord
Just ([ShiftModifier], TwoKey)

some characters cannot be represented as keypresses, like some non-printable characters (in arbitrary applications, not just the terminal emulator):

>>> char2keypress '\0' :: Maybe KeyChord
Nothing

case char2keypress c of {  Just ([],_) -> True;  Just ([ShiftModifier],_) -> True;  Nothing -> True;  _ -> False  }

the character that represents the keypress:

>>> keypress2char ([ShiftModifier], TwoKey) :: Maybe Char
Just '@'

some keypresses cannot be represented as characters, like keyboard shortcuts:

>>> keypress2char ([Command], CKey) :: Maybe Char
Nothing

>>> import Data.Char
>>> import Data.Maybe
prop> maybe True isAscii (keypress2char k)
TODO replace true with redo test