2.1.2 Comments

Pyret supports two forms of comments:
  • Single-line comments begin with a # symbol and extend to the end of the line:

    # This is an example of a single-line, standalone comment fun example(n): 1 + n # This single-line comment starts after some code end

  • Block comments begin with a #| symbol and end with a matching |#.

    fun example(n): #| This comment can extend over multiple lines |# 1 + n end

    While the text of a comment block contains everything between the #| and |# symbols, it is preferred to put them on their own lines, so they are visually distinctive and can easily be added or removed:

    #| prefer this style |#

    #| instead of this style |#

    The one exception is when block comments are being used to comment out sections of a single line of code:

    rectangle(30 #|width|#, 40 #|height|#, "solid", "red")

    They can be nested within each other, so long as the delimiters are matched:

    fun example(n): #| this is in a comment #| so is this and this |# and this |# 1 + n end

    Within a block comment, single-line comments are ignored:

    fun example(n): #| This is a block comment. Even though the next line starts a single-line comment # the block-comment ends here |# 1 + n end

    (Naturally, this style isn’t preferred, as it is easy to ignore the end-of-comment marker when reading quickly!)