[r6rs-discuss] [Formal] Change the "for" import syntax in libraries

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Name: Michael Lenaghan
Email: michaell at frogware.com
Type: Simplification
Priority: Minor
Component: Libraries
Version: 5.91
Section: 6.1 Library form (pg 21)
Dependencies: 6.4 Examples (pg 25)
Summary:
Change the "for" import syntax in libraries to make it easier to read.
Description:
In section 6.1 a library <import spec> is defined to be one of:
        <import set>
        (for <import set> <import phase> ...)
In section 6.4 an example uses the "for" syntax:
        (library (my-helpers values-stuff)
                (export mvlet)
                (import r6rs (for (my-helpers id-stuff) expand))
                ...)
The "for" syntax is already somewhat difficult to read since it places an 
identifier--in this case a compound identifier--in the middle of an 
English phrase. Unfortunately, it can get worse; an import set can contain 
nested clauses such as "only", "except", "add-prefix", and "rename" 
pushing the import phase even further from the "for":
        (library (my-helpers values-stuff)
                (export mvlet)
                (import r6rs (for (add-prefix (my-helpers id-stuff) 
mh-id:) expand))
                ...)
It becomes more difficult to read such syntax than it needs to be.
Recommendation:
The "for" clause can place the import phase(s) immediately after the 
"for":
        (for <import phase> ... <import set>)
I think that makes the examples easier to read:
        (library (my-helpers values-stuff)
                (export mvlet)
                (import r6rs (for expand (my-helpers id-stuff)))
                ...)
        (library (my-helpers values-stuff)
                (export mvlet)
                (import r6rs (for expand (add-prefix (my-helpers id-stuff) 
mh-id:)))
                ...)
The underlying implementation may or may not be marginally more difficult, 
but if it is I think the effort is worth the trade-off.
Anoher variant on this idea is:
        (for <import phases> <import set>)
Where <import phases> (note the plural) is:
        <import phase>
        (<import phase> ...)
For multiple import phases that would end up looking like this:
        (library (my-helpers values-stuff)
                (export mvlet)
                (import r6rs (for (expand run) (add-prefix (my-helpers 
id-stuff) mh-id:)))
                ...)
(The fact that a "meta" import phase is represented as a list may make 
this undersirable.)