Unit Mismatch error for wei_value operation

[eltNEG]

Version Information

• vyper Version: https://vyper.online [Wednesday, November 7, 2018]
  and
• vyper Version: 0.1.0b4
• pyethereum Version: x.x.x
• OS: linux
• Python Version (python --version): 3.6.6

What's your issue about?

Unexpected error while compiling my contract. Check the second to the last line in the snippet below
ERROR: vyper.exceptions.TypeMismatchException: line 177:8 Unit mismatch: {'wei': 1} {}
Why do I need to convert amount to wei_value again when it has already been declared in the function argument?
Code:

@public
@constant
def func(amounts: wei_value[100]) -> bool:
    total: wei_value = as_wei_value(0, "wei")

    # calculate total
    for amount in amounts:
        total += amount # Error: mismatch units

    return True

How can it be fixed?

Convert amount to wei_value

@public
@constant
def func(amounts: wei_value[100]) -> bool:
    total: wei_value = as_wei_value(0, "wei")
    
    for amount in amounts:
        total = as_wei_value(amount, "wei") # No error
    return True

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[fubuloubu]

Ah, great catch. #1054 should probably account for this. What do you think @jacquesww? (Iterators should carry types and units)

Edit: wait, 1054 doesn't make sense. I think there is an earlier PR for Iterators

[jacqueswww]

Starting on this.