Debugging

Inspecting compiled output

JVM class files

Use javap (from the JDK) to disassemble compiled class files:

skotch emit --target jvm hello.kt -o HelloKt.class
javap -c HelloKt.class

DEX files

Use dexdump (from the Android SDK build-tools) to inspect DEX output:

skotch emit --target dex hello.kt -o classes.dex
dexdump -d classes.dex

LLVM IR

The LLVM IR output is human-readable text:

skotch emit --target llvm hello.kt -o hello.ll
cat hello.ll

Normalized output

Use --norm-out to write a normalized text form alongside binary output. This strips cosmetic differences and makes the structure easier to read:

skotch emit --target jvm hello.kt -o HelloKt.class --norm-out hello.norm.txt
cat hello.norm.txt

Using the REPL for debugging

The REPL is useful for testing individual functions and expressions:

skotch repl

skotch> fun double(x: Int): Int = x * 2
skotch> println(double(21))
42

Declarations accumulate across turns, so you can build up state incrementally and test as you go.

Compiler errors

Skotch prints diagnostics to stderr when compilation fails. Common categories:

Error	Meaning
Parse error	Syntax not recognized (check for unsupported features)
Unresolved reference	Function or variable name not found
Type mismatch	Argument type doesn’t match parameter type
Feature not yet supported	Using a Kotlin feature that Skotch doesn’t compile yet

Tip

If you get a “not yet supported” diagnostic, check the Language Overview for workarounds. Many features that need classes can be approximated with top-level functions and extension functions.