A type constructor F[_] together with an operation forall A, B. (A => B) => F[A] => F[B] that satisfies FunctorLaw,
i.e. that a series of maps may be freely rewritten as a single map on a composed function, and that the identity function, lifted, is a no-op.
A good example from scalaz
def map[A, B](fa: F[A])(f: (A) ⇒ B): F[B]
| object Main extends App { | |
| def toOpt(s: Set[String]): Option[String] = s match { | |
| case x if !x.isEmpty => Some(x.mkString(" ")) | |
| case _ => None | |
| } | |
| val a: Set[String] = Set() | |
| val b: Set[String] = Set("a", "b") | |
| println(s"a = ${toOpt(a)}") | |
| println(s"b = ${toOpt(b)}") |
| val scalacFlags = Seq( | |
| "-deprecation", | |
| "-encoding", "UTF-8", | |
| "-feature", | |
| "-language:existentials", | |
| "-language:experimental.macros", | |
| "-language:higherKinds", | |
| "-language:implicitConversions", | |
| "-unchecked", | |
| "-Xfatal-warnings", |
| !/bin/sh | |
| count=0 | |
| interval=60 | |
| while true | |
| do | |
| echo -ne "$(date +%Y-%m-%dT%H:%M:%S) | $((count/interval)) mins : $1"'\r' | |
| let count+=interval | |
| sleep $interval | |
| done |
...perfection is finally attained not when there is no longer anything to add, but when there is no longer anything to take away...
-- Antoine de Saint-Exupéry
| #!/bin/bash | |
| rm -vrf /System/Library/Extensions/zfs.kext | |
| rm -vrf /System/Library/Filesystems/zfs.fs | |
| rm -vf /usr/lib/libzfs.dylib | |
| rm -vrf /usr/lib/libzfs.dylib.dSYM | |
| rm -vf /usr/lib/libzpool.dylib | |
| rm -vrf /usr/lib/libzpool.dylib.dSYM | |
| rm -vf /usr/local/bin/zoink | |
| rm -vrf /usr/local/bin/zoink.dSYM |
#Outstanding FP, CS, and other books we like.
| # pushd /opt/local/var/macports/registry | |
| # mv registry.db registry.db.old | |
| # sqlite3 registry.db.old | |
| sqlite> .load /opt/local/var/macports/sources/rsync.macports.org/release/base/src/cregistry/macports.sqlext | |
| sqlite> .mode insert | |
| sqlite> .output dump_all.sql | |
| sqlite> .dump | |
| sqlite> .exit |
| co = checkout | |
| br = branch | |
| ci = commit | |
| st = status -sb | |
| lg = log --color --graph --pretty=format:'%Cred%h%Creset -%C(yellow)%d%Creset %s %Cgreen(%cr) %C(bold blue)<%an>%Creset' --abbrev-commit | |
| ll = log --pretty=format:"%C(yellow)%h%Cred%d\\ %Creset%s%Cblue\\ [%cn]" --decorate --numstat | |
| ls = log --stat --oneline | |
| ld = log --pretty=format:'%C(auto) %h [%C(green)%ar%C(reset)] %C(blue) %cn %C(reset)%C(auto) %d %<|(5) %s' --graph --decorate --all | |
| f = "!git ls-files | grep -i" | |
| dl = "!git ll -1" |
| #!/bin/sh | |
| #.git/hooks/prepare-commit-msg | |
| original="$1" | |
| temp=`mktemp /tmp/git-XXXXX` | |
| ticket=`git branch | grep '^\*' |sed -e 's@.*/@@'` | |
| (printf "\n\n$ticket"; cat "$original") > "$temp" | |
| cat "$temp" > "$original" |
