Source Code

Encoding

Epsil's JavaScript API accepts a string. A host reading an Epsil source file should decode it as UTF-8 and should write identifiers in Unicode NFC form, as required by the MathJSON symbol contract.

The Epsil parser does not decode files or strip a byte-order mark. File I/O and decoding are the responsibility of the host. Inside a string literal, Unicode code points can also be written with escape sequences.

File Extension

The conventional file extension is .epsil.

MIME-type

The project uses text/epsil as its media-type convention. It is not a registered IANA media type.

Command line

Installing @cortex-js/compute-engine provides the epsil command:

epsil --eval "1 + 2"
epsil program.epsil
epsil --json program.epsil

With no file or --eval, epsil starts an interactive REPL when standard input is a terminal; otherwise it reads a program from standard input. The command applies a 10-second evaluation limit by default. Use --time-limit <milliseconds> to change it or --time-limit 0 to disable it. Run epsil --help for the complete option list.

See Epsil CLI for installation, output modes, REPL commands, diagnostics, and exit-status behavior.

Hashbang Comment

A hashbang comment can appear at the absolute start of the source and is ignored by the Epsil parser. It can be used to run an executable source file through the installed command:

#!/usr/bin/env epsil