The shorter this post is, the happier I’ll be. It’s meant to be more of a reference as I inevitably have to add new things. Assuming I remember to update it of course.

Words

fun

Function literal. Has special syntax for varargs and such. The last set of parens/braces is the body.

Argument to a function that is call-by-name, not call-by-value. That is, it’s only evaluated when the function body refers to it, and then it is evaluated each time.

lazy

Call-by-need function argument. Like the modifier form of fun, but with more caching. So it won’t work so well as a loop body, for instance.

Can modify a variable’s definition, as in x := lazy f(4), to defer the evaluation until it is needed, if it even is.

op

Used to create new (infix) operators, for example op+ := ..., like in Standard ML. Associativity and precedence declarations are still to come; they may just be infix{r,l,} statements like Haskell or something.

case

Pattern matching. The details aren’t really certain just yet, as proper matching is hilariously ill-suited to dynamic languages like this is. So maybe just a .matches method like Ruby’s ===.

var

Introduces a new variable. Indicates that you mean to shadow a variable in an enclosing scope (if there is one), rather than overwrite it.

Symbols

:=

Assignment. Local to the nearest enclosing (lexical) scope. Haven’t decided what to do about assigning to nonlocals yet. Also used in case, mostly just because it was already reserved.

.

Property lookup. Two in a row mean that the property itself starts with a dot (implying that it’s used for the machinery behind another function, like __python__ does.)

There are going to be a bunch more of these, most likely. I doubt I’m really going to keep := for case expressions, for instance.

This entry was posted on Tuesday, March 10th, 2009 at 5.06 pm and is filed under That language. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.