ZSH higher order functions
You can look at yogsototh's blogpost for the idea of higher order functions in zsh.
Examples and usage
Here are some examples:
$ mapa '$1*2' {1..3}
2
4
6
$ folda '$1+$2' {1..5}
15
$ folda '$acc+$x' {1..5}
15
$ filter 'echo $1|grep a >/dev/null' ab cd ef ada
ab
ada
$ map 'X $1:t Y' ~/.zsh/functional/src/*
X each Y
X filter Y
X fold Y
X map Y
$ map 'result $1' $(mapa '$1+5' $(mapa '$1*2' {1..3}))
result 7
result 9
result 11
$ echo "1\n2\n3" | mapa '$1*2' | mapa '$1+5' | map 'result $1'
result 7
result 9
result 11
Here are some examples with named functions:
$ insideXY(){print -- "X $1 Y"}
$ eachf insideXY a b c d
X a Y
X b Y
X c Y
X d Y
$ add(){print -- $(($1+$2))}
$ foldf add {1..5}
15
Please refer to the tests for complete specifications. The advantages of the cram tests are that they are validated and readable.
Furthermore, the commands will print out their --help
if they are provided no
arguments.
Naming conventions
I found the lambda expression versions most useful hence they have the shortest
(plain) name. Functions ending with an f
are those taking in a named
function and functions ending with an a
will take an arithmetic lambda
expression. The examples above should clarify the syntax.
map
or each
?
map
is simply each
with an implicit echo
, it should feel somewhat
intuitive for ruby developers. Note how mapa
exists but not eacha
, and the
contrary for mapf
and eachf
.
Reading from standard input
All functions will read from stdin if no arguments are given to them. Please
see tests/filter.t
For a test that lazily generates the first 10 primes.
Contributing
Good idea! Just add a test and implement the new functionality and send away your pull request! :)
Running the tests
We test like antigen does testing.
Creds
Yann Esposito for the HoF idea and big thanks to Sterling's blogpost for discovering and starting implementing the anonymous function features.