jcrben / bashfunc

A small Bash library for functional programming - map, filter, reduce and more

bashFunc

A small Bash library for functional programming. Right now it contains map, filter, reduce, forEach, some and split.

API

Callback

The callback is always the first argument and you can either use normal functions or a string with the function body inside of () as first argument.
These two code blocks are equal:

reduce '( echo $(( $1 + $2 )) )' 0 1 2 3 4 5
# 15

add() { echo $(($1 + $2)); }
reduce add 0 1 2 3 4 5
# 15

Arguments

As data input you can either use positional arguments or the function reads lines from the standard input - like the native mapfile command does - and takes those as arguments. The following example demostrates the two alternatives:

map '( echo $(( $1 + 10 )) )' 1 2 3 4 5
map '( echo $(( $1 + 10 )) )' < <(printf "%s\n" 1 2 3 4 5)
# 11
# 12
# 13
# 14
# 15

Compatibility

You can of course chain different commands together:

reduce '( echo $(( $1 + $2 )) )' < <(filter '( (( $1 % 2 )) )' < <(map '( echo $(( $1 + 10 )) )' 1 2 3 4 5))
# 39

Examples

Map

map '( echo $(( $1 + 10 )) )' < <(printf "%s\n" 1 2 3 4 5)
# 11
# 12
# 13
# 14
# 15

Filter

filter '( (( $1 % 2 )) )' < <(printf "%s\n" 1 2 3 4 5)
# 1
# 3
# 5

Reduce

The second argument, in this case the 10, is the starting value of the accumulator.

reduce '( echo $(( $1 + $2 )) )' 10 < <(printf "%s\n" 1 2 3 4 5)
# 25

ForEach

forEach '( notify-send $1 )' < <(printf "%s\n" 1 2 3 4 5)

Some

The some function tests whether at least one element passes the test implemented by the provided function.

some '((( $1 % 2 )))' < <(printf "%s\n" 1 2 3 4 5)
# echo $?
# 0

Split

The API for this function is quite different. The first argument is a string and the second argument takes a seperator.

split 'Hello,World,Good,Evening' ','
# Hello
# World
# Good
# Evening