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comp syntax
comp do
x <- effect() # effectful bind
{:ok, y} = expr # pure pattern match
z = expr # pure assignment
end
Handler installation
comp |> Eff1.with_handler(args) |> Eff2.with_handler(args) |> Comp.run!()
Handler order is independent. EffectLogger must be innermost.
Effect overview
State & Environment
| Effect | Operations | Handler |
|---|
| State | get/0,1, put/1,2, modify/1,2, gets/1,2 | State.with_handler(comp, initial, opts) |
| Reader | ask/0,1, asks/1,2, local/2,3 | Reader.with_handler(comp, value, opts) |
| Writer | tell/1,2, peek/0,1, listen/1,2, pass/1,2, censor/2,3 | Writer.with_handler(comp, initial, opts) |
Error & Resources
| Effect | Operations | Handler |
|---|
| Throw | throw/1, catch_error/2 | Throw.with_handler(comp) |
| Bracket | bracket/3, bracket_/3, finally/2 | Pure combinator |
Value Generation
| Effect | Operations | Prod handler | Test handler |
|---|
| Fresh | fresh_uuid/0 | Fresh.with_uuid7_handler() | Fresh.with_test_handler() |
| Random | random/0, random_int/2, random_element/1, shuffle/1 | Random.with_handler() | Random.with_seed_handler(seed: N) |
Collections
| Combinator | fx_map/2, fx_reduce/3, fx_each/2, fx_filter/2 |
|---|
| FxList | Full Yield support |
| FxFasterList | Higher perf, limited Yield |
Concurrency
| Effect | Key ops | Handler |
|---|
| FiberPool | fiber/1, await/1, await!/1, await_all/1, scope/1,2, map/2 | FiberPool.with_handler(comp) |
| Channel | new/1, put/2, take/1, close/1, put_async/2, take_async/1 | Channel.with_handler(comp) |
| Brook | from_enum/1, map/2,3, filter/2,3, each/2, reduce/3, to_list/1 | Pure combinator |
| Parallel | all/1, race/1, map/2 | Parallel.with_handler(comp) |
| AtomicState | get/0,1, put/1,2, modify/1,2, cas/2,3 | AtomicState.with_agent_handler(comp, init) |
Persistence
| Effect | Operations | Handler |
|---|
| Command | execute/1 | Command.with_handler(comp, fn) |
| Transaction | transact/1, rollback/1, try_transact/1 | Transaction.Ecto.with_handler(repo) / Transaction.Noop.with_handler(comp) |
External Integration
| Module | Key functions |
|---|
| Port | request/3, request!/3; with_handler/2,3, with_test_handler/2,3, with_fn_handler/2,3, with_stateful_handler/4 |
| Port.EffectfulFacade | defcallback, __key__ helpers |
| Repo | insert/1,2, update/1,2, delete/1,2, get/2,3, get_by/2,3, all/1,2, one/1,2 + bangs |
| Adapter | use Skuld.Adapter, contract: M, impl: I, stack: &f/1 |
| AsyncCoroutine | run/2,3, run_sync/2,3, cancel/1,2 |
Logging & Durability
| Module | Key functions |
|---|
| EffectLogger | with_logging/1,2,3, with_resume/3,4, mark_loop/1 |
| SerializableCoroutine | new/2, get_log/1, serialize/1, deserialize/1 |
Query & Batching
| Module | Key functions |
|---|
| Query.Contract | deffetch, with_executor/2,3, with_cached_executor/2,3, with_cached_executors/2 |
| QueryBlock | query do ... end, defquery, defqueryp |
Running computations
| Function | Behaviour |
|---|
Comp.run(comp) | Returns {result, env} |
Comp.run!(comp) | Raises on Throw/Suspend |
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