Windows
Compatible applications
Quick Facts
Basic information about this file format
Extension
.MLYACC
File Type
ML-Yacc Parser Generator Input
Category
Programming
Best first step
Use compatible software
Quick Summary
A practical overview of the .mlyacc file format
The mlyacc file format is a specialized input file used by the ML-Yacc parser generator, which is a tool primarily associated with the Standard ML (SML) programming language. It serves as a specification file that defines the grammar of a language in Backus-Naur Form (BNF). An mlyacc file typically…
File extension
.MLYACC
File type
ML-Yacc Parser Generator Input
Category
Programming
Recommended action
Open with a trusted compatible app
How to open a .mlyacc file
Start with a trusted app that supports this format
- Check the file extension carefully and confirm that the file name really ends with .mlyacc.
- Use software that supports this file type. If one app does not work, try another compatible program for the same platform.
- Update the application if the file was created by a newer version of the software.
- Scan files from unknown sources before opening them, especially documents, archives, scripts, installers, and executable files.
What is a .mlyacc file?
File extension details and usage information
The mlyacc file format is a specialized input file used by the ML-Yacc parser generator, which is a tool primarily associated with the Standard ML (SML) programming language. It serves as a specification file that defines the grammar of a language in Backus-Naur Form (BNF). An mlyacc file typically contains three distinct sections: the user declarations, the ML-Yacc definitions (such as token declarations, precedence rules, and start symbols), and the grammar rules themselves, which include semantic actions written in SML code. When processed, the ML-Yacc tool reads this file and generates an SML source file containing a parser function. This parser is then used by compilers, interpreters, or data processing tools to transform a stream of tokens into an abstract syntax tree (AST) or other structured representations. It is a critical component for developers building domain-specific languages or full-scale programming language compilers within the SML ecosystem, providing a robust way to handle complex syntax parsing through LALR(1) parsing techniques.
Software Compatibility
Programs that may open or work with .mlyacc files
macOS
Compatible applications
Linux
Compatible applications
Mobile
Mobile applications
Can .mlyacc files be converted?
Options for saving or exporting this file to another format
In many cases, a .mlyacc file can be converted by opening it in compatible software and using an option such as Save As, Export, or Convert. The available output formats depend on the file type and the application used.
- Use the original software that created the file when possible.
- Check whether the application supports exporting to common formats.
- Be careful with online converters when working with private, business, or sensitive files.
- If conversion fails, the file may be corrupted, incomplete, encrypted, or not actually a .mlyacc file.
Why can't I open a .mlyacc file?
Common reasons this file type may not open correctly
Wrong software
The file may require a specific program that supports the .mlyacc format.
Incorrect extension
The file extension may have been renamed manually, even though the actual file format is different.
Corrupted file
The file may be incomplete, damaged during download, or transferred incorrectly.
Outdated app
Your software may need to be updated before it can open newer versions of this file format.
Frequently Asked Questions
Common questions about .mlyacc files
To open a .mlyacc file, use software that supports this file format.
- SML/NJ
- MLton
- Visual Studio Code (with SML extensions)
- TextMate
- GNU Emacs
Open the file in compatible software and look for options such as Save As, Export, or Convert. If no export option is available, the file may require a specialized converter or the original application that created it.
- Verify that the file extension is correct.
- Install or update compatible software.
- Try another application that supports this format.
- Check whether the file is corrupted, incomplete, or encrypted.
A file extension alone does not guarantee whether a file is safe or unsafe. Only open files from trusted sources, scan unknown files before opening them, and be especially careful with executable, script, archive, and document files.
File safety tips
Use caution with unknown files
Only open files from trusted sources. Before opening a .mlyacc file, scan it with antivirus software, verify that the file extension is expected, and avoid running unknown executable, installer, macro-enabled document, or script files.