Errors

This topic is meant to document all possible language errors in Pile

How Errors Work

In Pile, errors are represented like this:

pile: <ERROR>:
    at <FILENAME>:<LINE>:

    <CODE_LINE>
    ^
    <MESSAGE>
  + <HELP>

Types of Errors

Token Error

Represented as token error

Unterminated String

Unterminated String is thrown when the lexer finds a string literal without a matching closing delimiter (").

Here's a simple code example:

"I am unterminated
println

Invalid Character

Invalid Character is thrown when the lexer finds an invalid character in a value literal that you write.

Here's a simple code example:

# No cents in Pile
10¢

Illegal Character

Illegal Character is thrown when the lexer finds an illegal character in the file contents.

Here's a simple code example:

# Non-ascii characters are illegal
#    vvvvvv
proc привет
    "Привет, мир" println
    # But inside strings it's fine
end

Parse Error

Represented as parse error

Unexpected Token

Unexpected Token is thrown when the parser finds an unexpected token in the current parsing structure.

Here's a simple code example:

# Parser should expect a valid identifier for procs
proc /notanidentifier end
#    ^+++++++++++++++ here

Unexpected EOF

Unexpected EOF (End of File) is very similar to the Unexpected Token error, the only difference is that in place of an unexpected token, the parser finds nothing (the termination of the file).

Here's a simple code example:

proc
#   ^ should expect at least something :\

Unterminated Block

Unterminated Block is thrown when the parser doesn't find a mathing end keyword to close the block.

Here's a simple code example:

proc my_unterminated_procedure
  "Hello, Pile" println

# where's the end?

Unmatched Block

Unmatched Block is thrown when the parser does find an end block termination without the block beginning.

Here's a simple code example:

"hello" "pile" = if
  "hello" "pile" swap + println
end
end # bruh

Runtime Error

Represented as runtime error

Stack Underflow

Stack Underflow is thrown when the interpreter tries to execute an operation but the stack doesn't contain enough values on top for the operation.

Here's a simple code example:

1 2 3 + + + trace
#         ^ this operation only gets 6, there's no second value :\

Unexpected Type

Unexpected Type is thrown when the interpreter tries to execute an operation but the stack values' datatypes do not match properly.

Here's a simple code example:

"69" 420 = if
  #      ^ this is not JS please
  "bruh" println
end

Invalid Word

Invalid Word is thrown when the interpreter finds an undefined name in any part of the program.

Here's a simple code example:

GIRLFRIEND_PHONE_NUMBER println

Procedure Redefinition

Procedure Redefinition is thrown when the interpreter finds a second definition of a procedure in the program.

Here's a simple code example:

proc again
  "Hello, World" println
end

proc again # again!
  "Hello, World" println
end

Definition Redefinition

Definition Redefinition is basically the same error as Procedure Redefinition error but for Definitions.

Here's a simple code example:

def PI
    3.1415
end

def PI # again!
    3.1415
end

Empty Definition

Empty Definition is thrown when the interpreter can't bind a definition to any value. This happens because there's no value on top of the stack after the execution of the definition block.

Here's a simple code example:

def empty
  # Nothing here!
end

Unbound Variable

Unbound Variable is thrown when the interpreter can't bind a variable value a value on the stack. This happens because to define a variable, you need the amount of values on the stack corresponding to the variables you are defining.

Here's a simple code example:

# Nothing on the stack!
as no_value let # In this case, it should expect 1 value on the stack
  no_value println
end