infix operators, type 1: :_

 :_ :
    description:
        ket1 :_ ket2
        the infix operator for ket label colon space merge
        merge the labels of the two kets, with a colon and space in between, and multiply their coefficients
        useful for combining a category with a value
        effectively a short-cut for: ket1 _ |: > _ ket2

    examples:
        -- convert apple to "type" fruit:
        |fruit> :_ |apple>
            |fruit: apple>

    see also:
        extract-value, extract-category, + , - , _ , __ , .