Day 1 Fundamentals

This week covers the foundational concepts needed to start writing Go programs.

Core Concepts Learned

Compilation and Execution

• Go is a compiled language that produces native executables (binaries).
• Compilation happens at compile time to check code correctness; runtime is when the program executes.
• A binary/executable runs directly on the OS without an interpreter.

Running Code

• go run compiles and runs immediately (no saved binary).
• go build compiles and produces a reusable executable.

Program Structure

• A Go program must use package main to be executable.
• func main() is the single entry point; it takes no arguments and returns nothing.
• Programs communicate via side effects (printing, files, network), not return values.
• Go code is organized into packages; all .go files in a directory form one package.

Types and Variables

• Variables are statically typed; types are fixed at compile time.
• var declares explicitly; := declares + assigns inside functions only.
• Basic types learned: int, string, bool.

Control Flow

• if requires a boolean condition; no truthy/falsy values.
• for is the only loop construct (classic, while-style, infinite).
• for init/condition/post each allow exactly one expression.

Code Standards

• Go enforces formatting via gofmt / go fmt.
• gofmt enforces structure, not personal spacing preferences.

Modules

• A Go module is a directory with a go.mod file.
• go mod init is run once per project; optional for throwaway snippets.

Day 2: Core Go Building Blocks

Functions

• Functions can be defined outside main; main should only orchestrate.
• Functions can return multiple values.
• Errors are ordinary return values; nil means no error.

Collections

• A group of values of the same type can be created using []T{...}.
• len(x) returns how many values are in a group.
• Repetition over a group uses for _, v := range group.
• _ is used to ignore a value you don't need.

Design Patterns

• Functions should return early when an error occurs.
• Empty input must be handled explicitly.
• Multiple results (count, sum, min, max) can be computed in a single loop.
• Logic belongs in functions; printing belongs in main.

Next Steps

Continue working through exercises in each Day's folder and consolidate learnings from the curriculum.

failure is impossible