Cure
Verification-First Programming
Verification-First Programming
Comprehensive Guard Features Demonstration Shows all supported guard capabilities in Cure
# Comprehensive Guard Features Demonstration
# Shows all supported guard capabilities in Cure
module ComprehensiveGuardsDemo do
export [main/0]
import Std.Io [println/1]
# =============================================================================
# SECTION 1: Basic Comparison Guards
# =============================================================================
# Guards with literals - fully supported
def is_positive(x: Int): Bool when x > 0 = true
def is_positive(_x: Int): Bool = false
def is_negative(x: Int): Bool when x < 0 = true
def is_negative(_x: Int): Bool = false
def is_zero(x: Int): Bool when x == 0 = true
def is_zero(_x: Int): Bool = false
def is_nonzero(x: Int): Bool when x != 0 = true
def is_nonzero(_x: Int): Bool = false
# =============================================================================
# SECTION 2: Multi-Clause Functions
# =============================================================================
# Absolute value
def abs(x: Int): Int when x >= 0 = x
def abs(x: Int): Int = 0 - x
# Sign function
def sign(x: Int): Int when x > 0 = 1
def sign(x: Int): Int when x == 0 = 0
def sign(x: Int): Int = -1
# Fibonacci
def fib(n: Int): Int when n == 0 = 0
def fib(n: Int): Int when n == 1 = 1
def fib(n: Int): Int = fib(n - 1) + fib(n - 2)
# =============================================================================
# SECTION 3: Guard Sequences (AND/OR with literals)
# =============================================================================
# Small numbers (0-10)
def is_small(x: Int): Bool when x >= 0 and x <= 10 = true
def is_small(_x: Int): Bool = false
# Medium numbers (11-100)
def is_medium(x: Int): Bool when x > 10 and x <= 100 = true
def is_medium(_x: Int): Bool = false
# Extreme values
def is_extreme(x: Int): Bool when x < -100 or x > 100 = true
def is_extreme(_x: Int): Bool = false
# =============================================================================
# SECTION 4: Type Refinement with Guards
# =============================================================================
# Temperature classification
def classify_temp(celsius: Int): String
when celsius < -40 or celsius > 50 = "extreme"
def classify_temp(celsius: Int): String
when celsius >= 20 and celsius <= 25 = "comfortable"
def classify_temp(celsius: Int): String
when celsius < 0 = "freezing"
def classify_temp(celsius: Int): String
when celsius > 30 = "hot"
def classify_temp(_celsius: Int): String = "moderate"
# Age groups
def age_group(age: Int): String
when age < 0 = "invalid"
def age_group(age: Int): String
when age < 13 = "child"
def age_group(age: Int): String
when age < 20 = "teenager"
def age_group(age: Int): String
when age < 65 = "adult"
def age_group(_age: Int): String = "senior"
# Grade letters
def grade_letter(score: Int): String
when score >= 90 = "A"
def grade_letter(score: Int): String
when score >= 80 = "B"
def grade_letter(score: Int): String
when score >= 70 = "C"
def grade_letter(score: Int): String
when score >= 60 = "D"
def grade_letter(_score: Int): String = "F"
# =============================================================================
# SECTION 5: Real-World Applications
# =============================================================================
# Discount by age
def discount(age: Int): Float
when age < 12 = 0.5
def discount(age: Int): Float
when age >= 65 = 0.3
def discount(_age: Int): Float = 0.0
# Tax brackets
def tax_bracket(income: Int): Float
when income <= 10000 = 0.0
def tax_bracket(income: Int): Float
when income <= 40000 = 0.1
def tax_bracket(income: Int): Float
when income <= 100000 = 0.2
def tax_bracket(_income: Int): Float = 0.3
# Shipping weight
def shipping_cost(kg: Int): Int
when kg <= 0 = 0
def shipping_cost(kg: Int): Int
when kg <= 5 = 5
def shipping_cost(kg: Int): Int
when kg <= 20 = 10
def shipping_cost(_kg: Int): Int = 20
# =============================================================================
# SECTION 6: Comparison Operators
# =============================================================================
def test_gt(x: Int): String when x > 10 = "GT"
def test_gt(_x: Int): String = "LE"
def test_lt(x: Int): String when x < 10 = "LT"
def test_lt(_x: Int): String = "GE"
def test_gte(x: Int): String when x >= 10 = "GTE"
def test_gte(_x: Int): String = "LT"
def test_lte(x: Int): String when x <= 10 = "LTE"
def test_lte(_x: Int): String = "GT"
def test_eq(x: Int): String when x == 10 = "EQ"
def test_eq(_x: Int): String = "NE"
def test_neq(x: Int): String when x != 10 = "NE"
def test_neq(_x: Int): String = "EQ"
# =============================================================================
# SECTION 7: Utility Functions
# =============================================================================
# Clamp to 0-100
def clamp100(x: Int): Int when x < 0 = 0
def clamp100(x: Int): Int when x > 100 = 100
def clamp100(x: Int): Int = x
# =============================================================================
# SECTION 8: Recursive Functions
# =============================================================================
# Sum 0 to n
def sum_to(n: Int): Int when n <= 0 = 0
def sum_to(n: Int): Int = n + sum_to(n - 1)
# Factorial
def factorial(n: Int): Int when n <= 1 = 1
def factorial(n: Int): Int = n * factorial(n - 1)
# Power
def power(base: Int, exp: Int): Int when exp == 0 = 1
def power(base: Int, exp: Int): Int when exp == 1 = base
def power(base: Int, exp: Int): Int = base * power(base, exp - 1)
# =============================================================================
# SECTION 9: Guard Coverage
# =============================================================================
# Complete coverage
def classify(x: Int): String when x > 0 = "POS"
def classify(x: Int): String when x < 0 = "NEG"
def classify(_x: Int): String = "ZERO"
# Performance-ordered
def perf_test(x: Int): String when x == 42 = "ANSWER"
def perf_test(x: Int): String when x > 100 = "BIG"
def perf_test(x: Int): String when x > 0 = "POS"
def perf_test(x: Int): String when x < 0 = "NEG"
def perf_test(_x: Int): String = "ZERO"
# =============================================================================
# SECTION 10: Main Demo
# =============================================================================
def main(): Int =
println("=== COMPREHENSIVE GUARDS DEMO ===\n")
println("== Basic Comparisons ==")
println(is_positive(5))
println(is_negative(-3))
println(is_zero(0))
println(is_nonzero(7))
println("\n== Multi-Clause ==")
println(abs(5))
println(abs(-5))
println(sign(10))
println(sign(0))
println(sign(-10))
println(fib(7))
println("\n== Guard Sequences ==")
println(is_small(5))
println(is_medium(50))
println(is_extreme(200))
println("\n== Type Refinement ==")
println(classify_temp(22))
println(classify_temp(-50))
println(age_group(10))
println(age_group(70))
println(grade_letter(85))
println("\n== Real-World ==")
println(discount(10))
println(discount(70))
println(tax_bracket(25000))
println(shipping_cost(3))
println("\n== Comparisons ==")
println(test_gt(15))
println(test_lt(5))
println(test_gte(10))
println(test_eq(10))
println(test_neq(7))
println("\n== Utilities ==")
println(clamp100(-10))
println(clamp100(50))
println(clamp100(150))
println("\n== Recursive ==")
println(sum_to(10))
println(factorial(5))
println(power(2, 4))
println("\n== Coverage ==")
println(classify(5))
println(classify(-5))
println(classify(0))
println(perf_test(42))
println(perf_test(200))
println("\n=== ALL FEATURES COMPLETE! ===")
0
end