The content on this page is written in Chinese, and then traslated into English by machine. More accurate traslations are welcome at: https://github.com/wa-lang/man/tree/master/en

Ending's law: "Any application that can be compiled to WebAssembly, will be compiled to WebAssembly eventually."

1.3. wa command line

This section introduces the main functions of the wa command.

1.3.1. Help message

Enter the wa command or wa -h to view command line help information, as follows:

$ wa
NAME:
   Wa - Wa is a tool for managing Wa source code.

USAGE:
   wa [global options] command [command options] [arguments...]

VERSION:
   v0.8.1-mvp

COMMANDS:
   play   start Wa playground
   init   init a sketch Wa module
   build  compile Wa source code
   run    compile and run Wa program
   fmt    format Wa source code file
   test   test Wa packages
   yacc   generates parsers for LALR(1) grammars
   logo   print Wa text format logo

GLOBAL OPTIONS:
   --debug, -d              set debug mode (default: false)
   --trace value, -t value  set trace mode (*|app|compiler|loader)
   --help, -h               show help (default: false)
   --version, -v            print the version (default: false)

COPYRIGHT:
   Copyright 2018 The Wa Authors. All rights reserved.

See "https://wa-lang.org" for more information.

It has the following subcommands:

  • play：Start the local version of the playground；
  • init: initialize a Wa-lang project;
  • build: compile Wa-lang program;
  • run: compile and execute the Wa-lang program;
  • fmt: format the Wa-lang source code file;
  • test: execute the unit test of the Wa-lang project;
  • yacc: The W-lang version of yacc, used to generate parser code for LALR(1) grammar rules;
  • logo: Print the logo in Wa-lang and text version.

The build command has been shown in Section 1.1.1, and the play command has been shown in Section 1.2.5. This section briefly introduces other subcommands.

1.3.2 Initialize project

In Section 1.1.1 we have shown that wa run hello.wa executes a Wa-lang program in a separate file. But a single-file Wa-lang program has a huge limitation - it has only one file and cannot reference non-standard library code. For larger Wa-lang it is recommended to organize them in project mode.

Use the wa init command to initialize a Wa project. Take a look at the command line help first:

$ wa init -h
NAME:
   wa init - init a sketch Wa module

USAGE:
   wa init [command options] [arguments...]

OPTIONS:
   --name value, -n value     set app name (default: "hello")
   --pkgpath value, -p value  set pkgpath file (default: "myapp")
   --update, -u               update example (default: false)
   --help, -h                 show help (default: false)

This command has two important parameters, -name and -pkgpath, which correspond to the name of the project and the corresponding package path respectively. Each parameter has a default value, and you can use wa init to generate a hello project.

$ wa init
$ tree hello
hello
├── LICENSE
├── README.md
├── src
│   ├── main.wa
│   ├── mymath
│   │   └── math.wa
│   ├── mypkg
│   │   └── pkg.wa
│   └── zz_test.wa
├── vendor
│   └── 3rdparty
│       └── pkg
│           └── pkg.wa
└── wa.mod

7 directories, 8 files

The structure of the project will be introduced in Section 1.4.

1.3.3 Compile and execute

Enter the hello directory in the command line environment and enter wa build to build the wasm module in the output directory:

$ wa build
$ tree output/
output/
├── hello.wasm
└── hello.wat

1 directory, 2 files

The default output is the WASI specificated output/hello.wat and output/hello.wasm files. The exported wasm module can be executed with standard tools. You can also use the wa command to execute:

$ wa run ./output/hello.wasm
你好，凹语言！
5050
...

If you execute the wa run command without entry, it means that the current Wa-lang project will be compiled and executed. output/hello.wasm will be built first and then executed.

1.3.4 Format code

The wa fmt command is used to format code, and its command line help information is as follows:

$ wa fmt -h
NAME:
   wa fmt - format Wa source code file

USAGE:
   wa fmt [command options] [<file.wa>|<path>|<path>/...]

OPTIONS:
   --help, -h  show help (default: false)

The command line argument is the path to be formatted:

  • wa fmt file.wa formats the specified .wa file
  • wa fmt path formats all .wa files in the specified directory
  • wa fmt path/... recursively formats the .wa file in the specified path, including subdirectories

If no parameters are specified, all .wa files in the current directory will be formatted by default. If the current directory belongs to the Wa-lang project, the .wa files in all subdirectories will be formatted by default.

1.3.5 Unit test

The project generated by default will have a src/zz_test.wa test file with the following content:

func TestSum {
    assert(sum(100) == 5050, "sum(100) failed")
}

func ExampleSum {
    println(sum(100))

    // Output:
    // 5050
}

The result of testing sum(100) in the TestSum test function via the built-in assert function is 5050. In the ExampleSum example test function, pass //Output: to test that the output meets the expected results.

Execute the test through the wa test command in the command line environment of the project directory:

$ wa test
ok   myapp 104ms

1.3.6 Wa-lang version of yacc

yacc is a program for generating syntax parsers, a tool for compiler enthusiasts. The yacc of the Wa-lang language is transplanted from goyacc. For detailed usage, please refer to the related articles in the SmallTalk section of the wa-lang official website .

1.3.7 Print Logo

wa logo can output some logo patterns in text format, and readers can explore by themselves through the wa logo -h command.