WIT Commands

Morphir provides native support for WebAssembly Interface Types (WIT) through the morphir wit command family. These commands allow you to compile WIT source files to Morphir IR and generate WIT source from Morphir IR.

Overview

WIT (WebAssembly Interface Types) is the interface definition language for WebAssembly components. Morphir's WIT integration enables:

• Compiling WIT to IR: Parse WIT source and convert to Morphir's Intermediate Representation
• Generating WIT from IR: Convert Morphir IR back to WIT source
• Round-trip Validation: Verify semantic correctness through make + gen pipeline

Commands

morphir wit make

Compile WIT source to Morphir IR (frontend compilation).

morphir wit make [file.wit] [options]

Options:

Option	Description	Default
-s, --source <code>	Inline WIT source code	-
-f, --file <path>	Path to WIT file	-
-o, --output <path>	Output path for IR JSON	-
--warnings-as-errors	Treat warnings as errors	false
--strict	Fail on unsupported constructs	false
--json	Output result as pretty-printed JSON	false
--jsonl	Output as JSONL (one JSON object per line)	false
--jsonl-input <path>	Path to JSONL file for batch processing	-
-v, --verbose	Show detailed diagnostics	false

Examples:

# Compile a WIT file
morphir wit make example.wit -o example.ir.json

# Compile inline WIT source
morphir wit make -s "package test:example; interface foo { bar: func(); }" -o out.ir.json

# Pipe from stdin
cat example.wit | morphir wit make -o out.ir.json

# Get JSON output with diagnostics
morphir wit make example.wit --json --verbose

morphir wit gen

Generate WIT source from Morphir IR (backend generation).

morphir wit gen [file.ir.json] [options]

Options:

Option	Description	Default
-f, --file <path>	Path to IR JSON file	-
-o, --output <path>	Output path for WIT file	-
--warnings-as-errors	Treat warnings as errors	false
--json	Output result as JSON	false
--jsonl	Output as JSONL	false
-v, --verbose	Show detailed diagnostics	false

Examples:

# Generate WIT from IR
morphir wit gen example.ir.json -o example.wit

morphir wit build

Run the full WIT pipeline: WIT -> IR -> WIT with round-trip validation.

morphir wit build [file.wit] [options]

This command combines make and gen steps and validates that the round-trip conversion is semantically correct.

Options:

Option	Description	Default
-s, --source <code>	Inline WIT source code	-
-f, --file <path>	Path to WIT file	-
-o, --output <path>	Output path for regenerated WIT	-
--warnings-as-errors	Treat warnings as errors	false
--strict	Fail on unsupported constructs	false
--json	Output result as JSON	false
--jsonl	Output as JSONL	false
--jsonl-input <path>	Path to JSONL file for batch processing	-
-v, --verbose	Show detailed diagnostics	false

Examples:

# Full build pipeline with output
morphir wit build example.wit -o regenerated.wit

# Build with inline source
morphir wit build -s "package test:example; interface foo { type user-id = string; }"

# JSON output for CI integration
morphir wit build example.wit --json

Batch Processing with JSONL

For processing multiple WIT sources efficiently, use JSONL (JSON Lines) batch mode.

Input Format

Create a JSONL file with one JSON object per line:

{"name": "users", "source": "package app:users; interface users { type user-id = string; }"}
{"name": "orders", "file": "path/to/orders.wit"}
{"name": "products", "source": "package app:products; interface products { record product { id: string, name: string, } }"}

Each line must have either:

• source: Inline WIT source code
• file: Path to a WIT file

The name field is optional and defaults to the filename or line number.

Running Batch Processing

# Batch make
morphir wit make --jsonl-input sources.jsonl --jsonl

# Batch build
morphir wit build --jsonl-input sources.jsonl --jsonl

Output Format

JSONL output produces one JSON object per line:

Make output:

{"name":"users","success":true,"typeCount":1,"valueCount":0}
{"name":"orders","success":false,"error":"parse error at line 5"}

Build output:

{"name":"users","success":true,"roundTripValid":true,"typeCount":1,"witSource":"package app:users;\n..."}

Diagnostics

All WIT commands produce structured diagnostics for errors, warnings, and informational messages.

Severity Levels

• ERROR: Fatal issues that prevent compilation
• WARN: Potential issues that may indicate problems
• INFO: Informational messages about processing

Viewing Diagnostics

Use --verbose to see all diagnostics:

morphir wit make example.wit --verbose

Diagnostics include:

• Severity level
• Diagnostic code (when available)
• Descriptive message
• Source location (file, line, column)

JSON Diagnostic Format

When using --json or --jsonl, diagnostics are included in the output:

{
  "success": false,
  "error": "parse error",
  "diagnostics": [
    {"severity": "error", "code": "WIT001", "message": "unexpected token"}
  ]
}

Integration with Toolchain Framework

The WIT commands integrate with Morphir's toolchain framework. The WIT toolchain is registered as a native toolchain with three tasks:

Task	Target	Description
make	make	Compile WIT source to Morphir IR
gen	gen	Generate WIT from Morphir IR
build	build	Full pipeline with round-trip validation

Using via Toolchain API

import (
    "github.com/finos/morphir/pkg/toolchain"
    wittoolchain "github.com/finos/morphir/pkg/bindings/wit/toolchain"
)

// Create and register
registry := toolchain.NewRegistry()
wittoolchain.Register(registry)

// Execute tasks
executor := toolchain.NewExecutor(registry, outputDir, ctx)
result, err := executor.ExecuteTask("wit", "make", "")

Exit Codes

Code	Description
0	Success
1	General error (parse error, invalid input, etc.)

See Also

• WIT Type Mapping - How WIT types map to Morphir IR
• Toolchain Integration - Toolchain framework design