Style

cLogos style considerations

Style recommendations in cLogos are meant to support reading, discussion, and reflection. They are not correctness criteria.

Indentation is not syntax, it is optics (7 June 2026)

Logo is a medium for thinking.

That is why indentation is a diagrammatic cue, not a rule. The language ignores whitespace. The learner does not.

Historically, Logo inherited:

• line orientation from teletype culture,
• flat textuality from early Lisp read-eval-print loops.

This lead to a layout style without indentation, such as:

to foo :bar :baz
repeat 4 :bar + :baz
end

This layout, fostered in many Logo textbooks, is not forbidden. But the cLogos environment supports indentation as an editor feature, because

whitespace helps humans to see the structure of the instructions.

to foo :bar :baz
  repeat 4 :bar + :baz
end

and

to foo :bar :baz
  repeat 4 ~
    :bar + :baz
end

will be preset in the environment by default, still adjustable by the learners to their own taste, for instance:

to foo :bar :baz
  repeat 4 ~
         :bar + :baz
end

Logo's abbreviations (7 June 2026)

In Logo textbooks, the shorthands of procedure names are frequently used, like pr for print, op for output, fd for forward etc.

This habit may have one or more of these possible backgrounds:

• Machines with small memory could be more efficiently be used with shorter procedure names.
• A hacker culture fostered mnemonic codes as a sort of signature for the adepts, the "leet hackers" ("leet" = "elite").
• Shorthands of commands as verbs appeared as performative, spoken contractions like "going to" -> "gonna", or "because" -> "cause".
• The teletype keyboards in the 1960s were sluggish, so that children were relieved by typing shorter procedure names.
• Shorter aliases relieved younger children from correct spelling of the full procedure names.

The latter reason still justifies the traditional shortcuts for younger learners.

Therefore, cLogos preserves Logo’s historical abbreviations.

However, for clarity and comprehensibility, the environment prioritises full procedure names and will autocomplete shorthands to their expanded forms.

Object-orientation adds expressiveness not a paradigm

Although experimental in Berkeley Logo, still being worked on, and only optionally compiled into Berkeley Logo, the concept is implemented in cLogos as an extension layer: the Berkeley Logo Object System (BLOS).

However, BLOS does not change the way Logo programs are written. The core thinking model of Logo remains procedures and lists, just as the core thinking model of Common Lisp remains functions and macros. BLOS is Logo’s structured extension of identity, behaviour, and inheritance, just as CLOS is Common Lisp’s structured extension of dispatch and identity.

Both cLogos and Common Lisp can be used entirely without object orientation. The respective object systems provide additional expressive power but are not the dominant mode of expression.

Thus, plain Logo programming remains the primary pedagogical mode, and object orientation is introduced only when it provides clear, pedagogically meaningful and structurally useful advantages.