'''
A few simple but often needed tools.
'''
from typing import TypeVar, Optional


def toStr(d:dict)->str:
    '''
    prettyprint dict, using str (not repr) for elements in dict.
    This tostring function looks similar to how java prints it,
    '''
    return "{"+ (", ".join([str(k)+"="+str(v) for (k,v) in d.items()]))+"}"


def toTuple(d:dict) -> tuple:
    '''
    Converts dict into tuples of tuples. Used mainly to compute hash
    '''
    return tuple([(k,v) for (k,v) in d.items()])

T = TypeVar('T')
def val(v:Optional[T])->T:
    '''
    @return the value contained in the optional.
    Raises exception if the value is None. 
    '''
    if not v:
        raise ValueError("Value is not set")
    return v