Confusing error: "Standard constructors are never updatable, expected: atom (variable or literal)"

[tomjaguarpaw]

I wrote this program:

one :: Program
one = mconcat
    [ [program|
    main = \ => Int# 1#
    |]]

The error was

error: Standard constructors are never updatable, expected: atom (variable or literal)
    <EOF> 
    ^

which was extremely puzzling. I only discovered that I should use -> instead of => by looking around for other example programs.

[quchen]

Good catch! This is a case where the parser does a (tiny) bit of static code analysis. I’ll have to figure out how to supporess “expected...got” messages in Trifecta, because fixing this should involve two things: a better error message hinting at the kind of arrow, and no suggestion of an “expected atom”.