foo.m

// OLD

- (NSDictionary *)parsePerks:(NSArray *)perks {
    NSMutableArray *convertedPerks = [NSMutableArray arrayWithCapacity:[perks count]];
    for (NSDictionary *perk in perks) {
        PLPerk *convertedPerk = [[PLPerk alloc] initWithProgramName:[perk objectForKey:@"program_name"] 
                                                   shortDescription:[perk objectForKey:@"perk_title"] longDescription:[perk objectForKey:@"perk_desc"] 
                                                           location:[self parseLocation:[perk objectForKey:@"locations"]]];
        [convertedPerks addObject:convertedPerk];
        [convertedPerk release];
    }
    return convertedPerks;
}

- (FKOption *)parseLocation:(NSArray *)locations {
    return locations == nil || [locations count] == 0 ? [FKOption none] : [FKOption fromNil:[[locations objectAtIndex:0] objectForKey:@"geo_location"]];
}


// NEW

- (NSDictionary *)parsePerks:(NSArray *)perks {
    NSArray *parsedPerks = [perks map:[NSArray liftFunction:functionTS(self, perkFromDictionary:)]];
    return [parsedPerks groupByKey:functionS(programName)];
}

- (PLPerk *)perkFromDictionary:(NSDictionary *)perk {
    return [[[PLPerk alloc] initWithProgramName:[perk objectForKey:@"program_name"] shortDescription:[perk objectForKey:@"perk_title"] 
                                   longDescription:[perk objectForKey:@"perk_desc"] location:[self parseLocation:[perk objectForKey:@"locations"]]] autorelease];  
}

- (FKOption *)parseLocation:(NSArray *)locations {
    return locations == nil || [locations count] == 0 ? [FKOption none] : [FKOption fromNil:[[locations objectAtIndex:0] objectForKey:@"geo_location"]];
}