Improved errors

[matthew-healy]

Syntax Errors

Invalid Token

Example program

~

Error report

Syntax error - invalid token

  ┌─ file_name.uplp-0:1:1
  │
1 │ ~
  │ ^

You may wish to try deleting this character and running the program again.

Unexpected end of file

Example program

let x = 1

Error report

Syntax error - unexpected end of file

  ┌─ file_name.uplp-0:1:1
  │
1 │ let a = 1
  │          ^

I was looking for an "in" but I reached the end of the file without finding it.

Unexpected token

Example program

let x = 1 let y = 2 in y

Error report

Syntax error - unexpected token 'let'

  ┌─ file_name.uplp-3:1:11
  │
1 │ let x = 1 let y = 2 in y
  │           ^^^

I wasn't able to work out what you meant by this.

Type Errors

Type mismatch

Example program

1 + ()

Error report

Type error - type mismatch

  ┌─ file_name.uplp-3:1:11
  │
1 │ 1 + ()
  │     ^^

Expected a Num, but found Unit.

Evaluation Errors

Division by zero

Example program

let zero = 0 in 1 / zero

Error report

Evaluation error - division by zero

  ┌─ file_name.uplp-3:1:11
  │
1 │ let zero = 0 in 1 / zero
  │                 ^^^^^^^^

The above expression resulted in division by zero, which is invalid.