This directory contains working examples demonstrating the Zoneinfo library's capabilities.

examples/
├── api/                      # Individual API examples (desktop, non-SPARK)
├── workflows/
│   ├── desktop/              # Real-world workflows using String (non-SPARK)
│   └── spark/                # Same workflows using Bounded_String (SPARK)
└── examples.gpr

The workflows/desktop/ and workflows/spark/ directories contain the same use cases implemented differently:

Compare matching examples to see how SPARK constraints affect code structure.

# Build all examples
alr exec -- gprbuild -P examples/examples.gpr

# Or from the examples directory
cd examples
alr exec -- gprbuild -P examples.gpr

Executables will be placed in examples/bin/.

./examples/bin/local_to_utc_to_zone

The "hello world" of timezone programming:

• Get current local time
• Convert to UTC
• Convert to another timezone (Pacific/Fiji)
• Display times as ISO 8601 strings

./examples/bin/epoch_and_duration

Working with epoch timestamps and durations:

• Parse ISO 8601 datetime string
• Parse ISO 8601 duration string (PT3H30M)
• Add duration to instant
• Convert between timezones
• Calculate duration between times
• Round-trip verification

./examples/bin/zoned_arithmetic

Arithmetic operations on zoned datetime values:

• Add/subtract durations from instants
• Duration arithmetic (+, -, negation)
• DST transition detection
• Calculate elapsed time between instants

./examples/bin/scheduling_across_zones

Real-world business scenario:

• Schedule a meeting at 2pm New York
• 90-minute meeting duration
• Show times for participants in Tokyo, London, Sydney
• Calculate timezone offset differences

• Result Monad Pattern: All operations return Result[T, Error]
• NO EXCEPTIONS: Functional error handling with explicit error paths
• Zoneinfo.API Facade: Public API for library operations
• ISO 8601 Parsing/Formatting: Full datetime and duration support
• Duration Math: Operator overloading for intuitive arithmetic
• DST Handling: Automatic daylight saving time transitions

with Zoneinfo.API;            use Zoneinfo.API;
with Zoneinfo.API.Desktop;    use Zoneinfo.API.Desktop;
with Zoneinfo.API.Parse;      use Zoneinfo.API.Parse;
with Zoneinfo.API.Format;     use Zoneinfo.API.Format;
with Zoneinfo.API.Operations; use Zoneinfo.API.Operations;

procedure Example is
   --  Parse datetime
   Civil_Result : constant Civil_Result.Result :=
     From_ISO_8601 ("2025-12-04T14:30:00");
begin
   if Civil_Result.Is_Ok (Civil_Result) then
      declare
         C : constant Civil := Civil_Result.Value (Civil_Result);
      begin
         --  Format to string (use To_String for desktop code)
         Put_Line (To_String (To_ISO_8601 (C)));
      end;
   end if;
end Example;

• Main README - Library overview and installation
• Software Requirements Specification
• Software Design Specification
• Test Suite - Comprehensive usage examples

Copyright (c) 2025 Michael Gardner, A Bit of Help, Inc.

Licensed under the BSD-3-Clause License. See ../LICENSE for details.