# File Version: 1.1.0

# /examples/24_first_class_funcs.rc

# Execution: ./target/release/rustcript examples/24_first_class_funcs.rc

print '--- 24 FIRST-CLASS FUNCTIONS ---'

# 1. Basic Assignment

print '1. Assigning Function to Variable...'

function add a b [

res a + b

return res

]

function subtract a b [

res a - b

return res

]

# Assign 'add' function to 'math_op' variable

math_op = add

print ' math_op is now: {math_op}'

# Call via variable

result = math_op(10, 5)

print ' math_op(10, 5) = {result}'

# Reassign

math_op = subtract

print ' math_op is now: {math_op}'

result = math_op(10, 5)

print ' math_op(10, 5) = {result}'

# 2. Passing Functions as Arguments

print ' '

print '2. Higher-Order Functions...'

function process_numbers list op_func [

print ' Processing list with {op_func}...'

new_list = {}

foreach n in list [

# Call the passed function

val = op_func(n, 2)

method new_list.push(val)

]

return new_list

]

data = {1, 2, 3, 4}

print ' Data: {data}'

# Pass 'add' (adds 2 to everything)

res1 = process_numbers(data, add)

print ' Result (Add 2): {res1}'

# Pass 'subtract' (subtracts 2 from everything)

res2 = process_numbers(data, subtract)

print ' Result (Sub 2): {res2}'

# 3. Functions in Data Structures

print ' '

print '3. Functions in Arrays/Maps...'

# In Vector

funcs = {add, subtract}

op = funcs[0]

res = op(100, 100)

print ' funcs[0](100, 100) = {res}'

# In Map

api = {'sum': add, 'diff': subtract}

op = api.diff

res = op(50, 20)

print ' api.diff(50, 20) = {res}'

print '--- END ---'