Assuming we're talking about Algol 60, it really depends on what kind of source code. When you look at the more creative applications of call-by-name, for examp

Assuming we're talking about Algol 60, it really depends on what kind of source code. When you look at the more creative applications of call-by-name, for example, it looks utterly alien. Or stuff like label arguments and switches. OTOH if you disregard those, the rest is simple to understand because there isn't much of it. E.g. there's a grand total of three types: integer, real, and Boolean. There are no structs, pointers, or really any derived types (it has arrays, but they aren't technically types but rather an orthogonal property of variables). But, for the same reason, it's not particularly useful. The lack of pointers especially limits what you can do with it, even if you use it for its original primary purpose (reference implementations of algorithms).