From ffd02244cd4dff35c41f87a4ccde860928cfdc79 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C5=82awomir=20=C5=9Aled=C5=BA?= <slawomir.sledz@gmail.com>
Date: Tue, 15 Aug 2017 23:43:11 +0200
Subject: [PATCH] Initial import

---
 examples/example.sh |  49 +++++++++
 src/fun.sh          | 236 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 285 insertions(+)
 create mode 100755 examples/example.sh
 create mode 100755 src/fun.sh

diff --git a/examples/example.sh b/examples/example.sh
new file mode 100755
index 0000000..a2dbba8
--- /dev/null
+++ b/examples/example.sh
@@ -0,0 +1,49 @@
+#!/bin/bash
+
+source ../src/fun.sh
+
+seq 1 4 | sum
+seq 1 4 | product
+factorial 4
+seq 1 4 | scanl lambda a b . 'echo $(add $a $b)'
+echo map mul
+seq 1 4 | map lambda a . 'echo $(mul $a 2)'
+echo map sub
+seq 1 4 | map lambda a . 'echo $(sub $a 2)'
+echo map add
+seq 1 4 | map lambda a . 'echo $(add $a 2)'
+echo map div
+seq 1 4 | map lambda a . 'echo $(div $a 2)'
+echo map mod
+seq 1 4 | map lambda a . 'echo $(mod $a 2)'
+echo 'list & head'
+list 1 2 3 4 5 | head
+list {1..2} | append {3..4} | prepend {99..102}
+list {1..2} | unlist
+list {1..10} | head
+list {1..10} | drop 7
+list {1..10} | take 3
+list {1..10} | last
+list {1..10} | map λ a . 'echo $(mul $a 2)'
+
+id() { 
+  λ x . '$x' 
+}
+
+id <<< 'echo :)'
+
+foobar() { 
+  product | λ l . 'list {1..$l}' | sum | md5sum 
+}
+
+list {1,2,3} | foobar
+
+echo -n abcdefg | revers_str                         # gfedcba
+echo -n abcdefg | splitc | join , '[' ']'            # [a,b,c,d,e,f,g]
+echo -n abcdefg | splitc | revers | join , '[' ']'   # [g,f,e,d,c,b,a]
+
+echo -n ' abcdefg' | splitc | foldr lambda a b . 'echo $a$b'  # gfedcba
+
+echo 'ls' | try λ cmd status ret . 'echo $cmd [$status]; echo $ret'
+
+list {1..10} | filter lambda a . '[[ $(mod $a 2) -eq 0 ]] && ret true || ret false' | join , '[' ']'  # [2,4,6,8,10]
diff --git a/src/fun.sh b/src/fun.sh
new file mode 100755
index 0000000..263b7f3
--- /dev/null
+++ b/src/fun.sh
@@ -0,0 +1,236 @@
+#!/bin/bash
+
+drop() {
+  command tail -n +$(($1 + 1))
+}
+
+take() {
+  command head -n ${1}
+}
+
+tail() {
+  drop 1
+}
+
+head() {
+  take 1
+}
+
+last() {
+  command tail -n 1
+}
+
+list() {
+  for i in "$@"; do
+    echo "$i"
+  done
+}
+
+unlist() {
+  cat - | xargs
+}
+
+append() {
+  cat -
+  list "$@"
+}
+
+prepend() {
+  list "$@"
+  cat -
+}
+
+
+lambda() {
+
+  lam() {
+    local arg
+    while [[ $# -gt 0 ]]; do
+      arg="$1"
+      shift
+      if [[ $arg = '.' ]]; then
+        echo "$@"
+        return
+      else
+        echo "read $arg;"
+      fi
+    done
+  }
+
+  eval $(lam "$@")
+
+}
+
+λ() {
+  lambda "$@"
+}
+
+map() {
+  local x
+  while read x; do
+    echo "$x" | "$@"
+  done
+}
+
+foldl() {
+  local f="$@"
+  local acc
+  read acc
+  while read elem; do
+    acc="$({ echo $acc; echo $elem; } | $f )"
+  done
+  echo "$acc"
+}
+
+foldr() {
+  local f="$@"
+  local acc
+  read acc
+
+  foldrr() {
+    local elem
+    read elem && acc=$(foldrr)
+    acc="$({ echo $acc; echo $elem; } | $f )"
+    echo "$acc"
+  }
+
+  foldrr
+}
+
+scanl() {
+  local f="$@"
+  local acc
+  read acc
+  echo $acc
+  while read elem; do
+    acc="$({ echo $acc; echo $elem; } | $f )"
+    echo "$acc"
+  done
+}
+
+mul() {
+  ( set -f; echo $(($1 * $2)) )
+}
+
+add() {
+  echo $(($1 + $2))
+}
+
+sub() {
+  echo $(($1 - $2))
+}
+
+div() {
+  echo $(($1 / $2))
+}
+
+mod() {
+  echo $(($1 % $2))
+}
+
+
+sum() {
+  foldl lambda a b . 'echo $(($a + $b))'
+}
+
+product() {
+  foldl lambda a b . 'echo $(mul $a $b)'
+}
+
+factorial() {
+  seq 1 $1 | product
+}
+
+splitc() {
+  cat - | sed 's/./&\n/g'
+}
+
+join() {
+  local delim=$1
+  local pref=$2
+  local suff=$3
+  echo $pref$(cat - | foldl lambda a b . 'echo $a$delim$b')$suff
+}
+
+revers() {
+  foldl lambda a b . 'append $b $a'
+}
+
+revers_str() {
+  cat - | splitc | revers | join
+}
+
+try() {
+  local f="$@"
+  local cmd=$(cat -)
+  ret="$(2>&1 $cmd)"
+  local status=$?
+  list "$cmd" $status $(list $ret | join \#) | $f
+}
+
+ret() {
+  echo $1
+}
+
+filter() {
+  local x
+  while read x; do
+    ret=$(echo "$x" | "$@")
+    $ret && echo $x
+  done
+}
+
+strip() {
+  local arg=$1
+  cat - | map lambda l . 'ret ${l##'$arg'}' | map lambda l . 'ret ${l%%'$arg'}'
+}
+
+buff() {
+  local cnt=-1
+  for x in $@; do
+    [[ $x = '.' ]] && break
+    cnt=$(add $cnt 1)
+  done
+  local args=''
+  local i=$cnt
+  while read arg; do
+    [[ $i -eq 0 ]] && list $args | "$@" && i=$cnt && args=''
+    args="$args $arg"
+    i=$(sub $i 1)
+  done
+  [[ ! -z $args ]] && list $args | "$@"
+}
+
+tup() {
+  list "$@" | join , '(' ')'
+}
+
+tupx() {
+  if [[ $# -eq 1 ]]; then
+    local arg
+    read arg
+    tupx "$1" "$arg"
+  else
+    local n=$1
+    shift
+    list "$@" | strip '\(' | strip '\)' | unlist | cut -d',' -f${n}
+  fi
+}
+
+tupl() {
+  tupx 1 "$@"
+}
+
+tupr() {
+  tupx 2 "$@"
+}
+
+zip() {
+  local list=$*
+  cat - | while read x; do
+    y=$(list $list | take 1)
+    tup $x $y
+    list=$(list $list | drop 1)
+  done
+}
+