on -package:numhask -package:ghc-lib-parser package:rio

on b u x y runs the binary function b on the results of applying unary function u to two arguments x and y. From the opposite perspective, it transforms two inputs and combines the outputs.

(op `on` f) x y = f x `op` f y

Examples

>>> sortBy (compare `on` length) [[0, 1, 2], [0, 1], [], [0]]
[[],[0],[0,1],[0,1,2]]

>>> ((+) `on` length) [1, 2, 3] [-1]
4

>>> ((,) `on` (*2)) 2 3
(4,6)

Algebraic properties

• (*) `on` id = (*) -- (if (*) ∉ {⊥, const
  ⊥})

• ((*) `on` f) `on` g = (*) `on` (f . g)

• flip on f . flip on g = flip on (g .
  f)

Configuration for how to create a LogFunc. Intended to be used with the withLogFunc function.

A contramap. Use this to wrap sub-loggers via mapRIO. If you are on base > 4.12.0, you can just use contramap.

A vesion of contramapMaybeGLogFunc which supports filering.

What color is the log func configured to use for secondary content? Intended for use by code which wants to optionally add additional color to its log messages.

Create a LogOptions value from the given Handle and whether to perform verbose logging or not. Individiual settings can be overridden using appropriate set functions. Logging output is guaranteed to be non-interleaved only for a UTF-8 Handle in a multi-thread environment. When Verbose Flag is True, the following happens:

• setLogVerboseFormat is called with True
• setLogUseColor is called with True (except on Windows)
• setLogUseLoc is called with True
• setLogUseTime is called with True
• setLogMinLevel is called with Debug log level

Create a LogOptions value which will store its data in memory. This is primarily intended for testing purposes. This will return both a LogOptions value and an IORef containing the resulting Builder value. This will default to non-verbose settings and assume there is a terminal attached. These assumptions can be overridden using the appropriate set functions.

This will print out the given message with a newline and disable any further stickiness of the line until a new call to logSticky happens.

ANSI color codes for secondary content in the log output. Default: "\ESC[90m" -- Bright black (gray)

O(n) Concatenate a list of ByteStrings.

Map a function over a ByteString and concatenate the results

O(n) cons is analogous to (:) for lists, but of different complexity, as it requires making a copy.

Lifted getContents

Lifted hGetContents

Lifted hGetNonBlocking

Lifted hPutNonBlocking

O(n) The partition function takes a predicate a ByteString and returns the pair of ByteStrings with elements which do and do not satisfy the predicate, respectively; i.e.,

partition p bs == (filter p xs, filter (not . p) xs)

O(1) Convert a Word8 into a ByteString

O(1) Extract the head and tail of a ByteString, returning Nothing if it is empty.

O(1) cons is analogous to (:) for lists.

O(1) Unlike cons, cons' is strict in the ByteString that we are consing onto. More precisely, it forces the head and the first chunk. It does this because, for space efficiency, it may coalesce the new byte onto the first 'chunk' rather than starting a new 'chunk'. So that means you can't use a lazy recursive contruction like this:

let xs = cons' c xs in xs

You can however use cons, as well as repeat and cycle, to build infinite lazy ByteStrings.

Lifted getContents

Lifted hGetContents

Lifted hGetNonBlocking

Lifted hPutNonBlocking