How to open .DL files on iOS
To open .DL files on iOS, use the Files app to open the .dl file in a text-capable viewer/editor; there is no broadly standard iOS Datalog runtime, so for execution you will typically transfer it to a desktop Datalog tool.
Step-by-step instructions
- Use the Files app to open the .dl file in a text-capable viewer/editor; there is no broadly standard iOS Datalog runtime, so for execution you will typically transfer it to a desktop Datalog tool.
Recommended software
- Textastic
- Kodex
- Files app
Alternative methods
- Open .DL in a browser-based viewer if desktop apps fail.
- Try opening .DL on iOS with a secondary app to rule out app-specific issues.
- Convert .DL only with trusted tools when direct opening is not possible.
Common issues
The file opens as gibberish or unreadable characters
Most .dl files for Datalog should be plain text. If it looks like binary data, it may not be a Datalog file (or it may be corrupted/incorrectly transferred).
- Open it in a plain text editor and check whether it contains readable rules/facts; if not, verify where the file came from.
- Re-download or re-transfer the file using a method that preserves text encoding (avoid copy/paste through apps that may alter characters).
A Datalog tool refuses to parse the .dl file
Different tools may accept different syntaxes; even within Datalog, dialect differences can cause parse errors.
- Confirm the tool’s expected syntax and compare it with the Datalog Text Representation specification.
- Look for common issues such as unsupported predicates, syntax differences, or encoding problems (for example, unusual quotes or non-UTF-8 text).
The operating system does not know what app to use
.dl is associated with Datalog text (application/vnd.datalog), but most systems do not ship with a dedicated Datalog IDE by default.
- Open the file in a text editor to confirm it is Datalog source.
- Install and use a Datalog system that supports .dl programs (for example, Soufflé) or keep using a text editor for viewing/editing.
Security note
.dl (Datalog) files are typically plain text rules/facts, not executables, but untrusted files can still be risky if fed into a complex parser/compiler (crashes or resource exhaustion are possible).