Add MVP for functional programming

src/func.sh

@@ -0,0 +1,32 @@
+#!/usr/bin/env bash
+
+func::list() {
+   for x in "$@"; do
+      echo "$x"
+   done
+}
+
+func::map() {
+   local -r fn="$1"
+   shift
+
+   for x in $(cat); do
+      "$fn" "$x"
+   done
+}
+
+func::reduce() {
+   local -r fn="$1"
+   local state="$2"
+
+   local -r coll="$(cat)"
+   local -r x="$(echo "$coll" | head -n1)"
+
+   if [ -z "$x" ]; then
+      echo "$state"
+   else
+      local -r new_state="$("$fn" "$state" "$x")"
+      local -r new_coll="$(echo "$coll" | tail -n +2)"
+      echo "$new_coll" | func::reduce "$fn" "$new_state"
+   fi
+}

src/main.sh

@@ -7,6 +7,7 @@ fi
 source "${SCRIPT_DIR}/src/arg.sh"
 source "${SCRIPT_DIR}/src/cheat.sh"
 source "${SCRIPT_DIR}/src/dict.sh"
+source "${SCRIPT_DIR}/src/func.sh"
 source "${SCRIPT_DIR}/src/health.sh"
 source "${SCRIPT_DIR}/src/misc.sh"
 source "${SCRIPT_DIR}/src/opts.sh"

test/func_test.sh

@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+
+inc() {
+   local -r x="$1"
+   echo $((x+1))
+}
+
+sum() {
+   local -r x="$1"
+   local -r y="$2"
+   echo $((x*y))
+}
+
+func_map() {
+   func::list 1 2 3 \
+      | func::map inc \
+      | test::equals "$(func::list 2 3 4)"
+}
+
+func_reduce() {
+   func::list 1 2 3 \
+      | func::reduce sum 10 \
+      | test::equals 60
+}
+
+test::run "map works" func_map
+test::run "reduce works" func_reduce