must

Documentation

Overview

Package must provides assertion functions that panic on failure.

When to Use

Use must functions when you are certain that operations should not fail and want to eliminate error handling boilerplate in situations where errors indicate programming bugs rather than runtime conditions.

Common scenarios:

• Parsing static/hardcoded data (URLs, JSON, regex patterns)
• Operations that should always succeed in your specific context
• Configuration parsing where failure means misconfiguration

When NOT to Use

Avoid must functions for:

• User input validation
• Network operations
• File I/O operations
• Any operation that can legitimately fail at runtime

Functions

• must.OK[T](value T, err error) T - returns value if err is nil, panics otherwise
• must.True[T](value T, condition bool) T - returns value if condition is true, panics otherwise
• must.NoErr(err error) - panics if err is not nil

Examples

// Static data parsing
baseURL := must.OK(url.Parse("https://api.example.com"))
pattern := must.OK(regexp.Compile(`^[a-z]+$`))

// Configuration validation
config := must.True(loadConfig(), config.IsValid())

// JSON unmarshaling of known-good data
var data Config
must.NoErr(json.Unmarshal(embeddedConfig, &data))

Index

• func NoErr(err error)
• func OK[T any](v T, err error) T
• func True[T any](v T, condition bool) T

Functions

func NoErr

func NoErr(err error)

NoErr panics if error is not nil.

must.NoErr(json.Unmarshal(staticJSON, &data))

func OK

func OK[T any](v T, err error) T

OK returns the value if error is nil, otherwise panics.

u := must.OK(url.Parse("https://example.com"))

func True

func True[T any](v T, condition bool) T

True returns the value if condition is true, otherwise panics.

result := must.True(logger.FromCtx(ctx))