HOWTO

--
-- Examples for h4sh
--
-- Authors: Don Stewart
--          Thomas Jaeger
--
-- Inspiration for this document based on "HANDY ONE-LINERS FOR SED",
-- compiled by Eric Pement <http://sed.sourceforge.net/sed1line.txt>
--
--
-- Most commands (other than unfolds) read from either a file argument or stdin
--

-- open a file
i

-- first line of a file/pipe (head -1)
hd

-- last line of a file/pipe (tail -1)
last

-- first @n@ lines (head -7)
take 7

-- drop first @n@ lines
drop 7

-- remove the first line
tl

-- remove the last line
init

-- reverse a file (tac)
reverse

-- print a string (echo)
show

-- find lines that match /pattern/ (grep)
filter 'matches "pattern"'

-- find lines that don't match /pattern/ (grep -v)
filter '\s->not(matches"pattern"s)'

-- replace all occurences of string1 with string2
map 'replace "string1" "string2'

-- add a character to the end of each line
map "snoc ','"

-- group lines of input that are equal
group

-- join two files side by side (paste)
zp f g

-- add a new line to the head of a file
cons "The first line"

-- double space a file
intersperse ''

-- an infinite sequence
iterate 'show.(+1).read' 0
unfoldr 'Just. ap(,)(show.(1+).read)' 1

-- a finite sequence
iterate 'show.(+1).read' 0 | take 10

-- repeat a string
rpt str

-- number each line of a file on left
zp <(iterate 'show.(+1).read' 0)
ap 'unlines.zipWith((.(" "++)).shows)[1..].lines'

-- count lines (wc -l)
length

-- remove duplicate lines (uniq)
nub

-- sort
srt

-- join lines of a file
concat
unwords
foldl '(++)'

-- print only lines 65 chars long
filter '(65==).length'

-- print only lines less than 65 chars
filter '(65>=).length'

-- print only lines greater than 65 chars
filter '(65<).length'

-- find all lines that equal "str"
filter '=="str"'

-- remove all lines that equal "str"
filter '/="str"'

-- remove the first occurence of the line "str"
delete str

-- find line 10
index 10

-- find the indices of a given line
indices str

-- reverse each line (rev)
map reverse

-- count lengths of each line
map show.length

-- upper case
map 'map toUpper'

-- lower case
map 'map toLower'

-- remove leading space from each line
map "dropWhile isSpace"

-- remove tailing whitespace
map "reverse.dropWhile isSpace.reverse"

-- center each line of a file
map "\s->(\t->t++s++t)(replicate(div(80-length s)2)' ')"

-- reverse words in a string, but not the string itself
words one two three | map reverse | unwords

-- turn a string into a list of string, suitable for passing to list functions
words one two three