Examples

Examples¶

Each example is a complete program in docs/examples/ that you can run and change. Run it from the repository root:

pixi run mojo run -I src docs/examples/<name>.mojo

The programs check their results with std.testing. Documentation tests also compile them through source and precompiled package imports at O0 and O3 with --Werror, then compare their output with the output shown on the site.

Start with pipelines¶

Example	What it shows	Page
`quickstart.mojo`	The smallest complete program: a one-stage `pipe`	Home
`callable_pipeline.mojo`	A pipeline of plain functions over a consumed list, ending in a fold	Pipelines tutorial
`callable_pipeline_generic.mojo`	Forwarding a pipeline through a generic function	Pipelines tutorial
`chained_pipeline.mojo`	A ten-stage chain with `piped(...).then(...)`: plain functions, closures and partials	fp.functions
`partial.mojo`	Binding leading arguments with `partial`; binding a keyword with a closure	fp.functions

Iterate and fold¶

Example	What it shows	Page
`iteration.mojo`	Lazy selection, ordered reduction and initial-first snapshots	Iteration tutorial
`iteration_chaining.mojo`	Consuming method chains, both list collectors and native `enumerate`	Iteration tutorial
`generic_fold.mojo`	One `fold_left` over scalars, SIMD vectors and a user-defined document	fp.iteration
`iteration_generic.mojo`	Returning `map` and `scan_left` adapters from generic functions	Iteration tutorial
`iteration_filtering_generic.mojo`	Returning filtering adapters from generic functions	Iteration tutorial
`terminal_generic.mojo`	Generic terminal wrappers that keep the callback's exact error	Iteration tutorial
`control_flow.mojo`	`while_loop`, `fori_loop` and carry/output `scan`	fp.control

Handle results and errors¶

Example	What it shows	Page
`results.mojo`	Stored domain errors versus raised callback failures	Results tutorial
`result_transform_generic.mojo`	Generic Result transformations	Results tutorial
`attempt_generic.mojo`	A generic transaction helper built on `attempt`	Results tutorial
`attempt_once.mojo`	Capturing the failure of a consuming thunk	fp.data
`result_once.mojo`	Consuming handlers in Result transformations and folds	fp.data

Store values in place¶

Example	What it shows	Page
`foundations.mojo`	Callbacks, folds, typed errors and a `Choice` matched together	Values stored in place
`optional.mojo`	Matching a standard `Optional` and a `Result`, with a guard	Values stored in place

Declare and match data¶

Example	What it shows	Page
`shapes.mojo`	A sum type matched with clauses, a guard, a context and a pair of values	Matching tutorial
`traffic_light.mojo`	Matching two values, and three with a plain one, by every combination of constructors	Matching tutorial
`expression.mojo`	Structural recursion over an inductive expression type: evaluation, rendering and rewriting, with `Next` and shared values	Inductive types tutorial
`file_tree.mojo`	Recursive fields in a `List` and an `Optional`	Recursion tutorial

Use algebra and effects¶

Example	What it shows	Page
`algebra_core.mojo`	`pure`, `map`, `flat_map` and `traverse` over four native carriers	fp.algebra
`algebra_choices.mojo`	Mapping, monadic bind, `map2`, `ap` and List's Cartesian combination	Algebra tutorial
`algebra_traversal.mojo`	`traverse` and `sequence`, early termination and empty input	Algebra tutorial
`effects_reader.mojo`	Pricing configuration with `ask`, `local` and a borrowed deferred callback	Effects tutorial
`effects_state.mojo`	Reading, updating and resetting a counter with State	Effects tutorial
`effects_writer.mojo`	Ordered logs with Writer, `tell`, `listen` and `censor`	Effects tutorial
`state_result.mojo`	How transformer order decides whether a failure keeps its state	fp.effects

Build an application¶

Example	What it shows	Page
`config_parser.mojo`	Parsing configuration lazily, collecting Results and validating with a fold that stops early	Application tutorial
`job_router.mojo`	Routing a queue of commands with guarded, raising clauses, a context and `attempt`	Application tutorial