---
layout: default
title: "Workflow"
---
This document details common workflow patterns when working with Dotty.
## Compiling files with dotc ##
From sbt:
```bash
> run <OPTIONS> <FILE>
```
From terminal:
```bash
$ ./bin/dotc <OPTIONS> <FILE>
```
Here are some useful debugging `<OPTIONS>`:
* `-Xprint:PHASE1,PHASE2,...` or `-Xprint:all`: prints the `AST` after each
specified phase. Phase names can be found by searching
`src/dotty/tools/dotc/transform/` for `phaseName`.
* `-Ylog:PHASE1,PHASE2,...` or `-Ylog:all`: enables `ctx.log("")` logging for
the specified phase.
* `-Ycheck:all` verifies the consistency of `AST` nodes between phases, in
particular checks that types do not change. Some phases currently can't be
`Ycheck`ed, therefore in the tests we run:
`-Ycheck:tailrec,resolveSuper,mixin,restoreScopes,labelDef`.
Additional logging information can be obtained by changes some `noPrinter` to
`new Printer` in `src/dotty/tools/dotc/config/Printers.scala`. This enables the
`subtyping.println("")` and `ctx.traceIndented("", subtyping)` style logging.
## Running tests ##
```bash
$ sbt
> partest --show-diff --verbose
```
## Running single tests ##
To test a specific test tests/x/y.scala (for example tests/pos/t210.scala):
```bash
> partest-only-no-bootstrap --show-diff --verbose tests/partest-generated/x/y.scala
```
Currently this will re-run some tests and do some preprocessing because of the
way partest has been set up.
## Inspecting Trees with Type Stealer ##
There is no power mode for the REPL yet, but you can inspect types with the
type stealer:
```bash
$ ./bin/dotr
scala> import test.DottyTypeStealer._; import dotty.tools.dotc.core._; import Contexts._,Types._
```
Now, you can define types and access their representation. For example:
```scala
scala> val s = stealType("class O { type X }", "O#X")
scala> implicit val ctx: Context = s._1
scala> val t = s._2(0)
t: dotty.tools.dotc.core.Types.Type = TypeRef(TypeRef(ThisType(TypeRef(NoPrefix,<empty>)),O),X)
scala> val u = t.asInstanceOf[TypeRef].underlying
u: dotty.tools.dotc.core.Types.Type = TypeBounds(TypeRef(ThisType(TypeRef(NoPrefix,scala)),Nothing), TypeRef(ThisType(TypeRef(NoPrefix,scala)),Any))
```
## Pretty-printing ##
Many objects in the dotc compiler implement a `Showable` trait (e.g. `Tree`,
`Symbol`, `Type`). These objects may be prettyprinted using the `.show`
method
