diff options
Diffstat (limited to 'txr.1')
| -rw-r--r-- | txr.1 | 24 |
1 files changed, 18 insertions, 6 deletions
@@ -4606,6 +4606,11 @@ The dotted notation can be used to write a function that accepts a variable number of arguments. To write a function that accepts variable arguments only, with no required arguments, use a single symbol. +The keyword symbol : can appear in the parameter list. It is not an argument, +but a separator between required parameters and optional parameters. +When the function is called, optional parameter for which arguments +are not supplied take on the value nil. + Functions created by lambda capture the surrounding variable bindings. @@ -4628,6 +4633,11 @@ Variadic funcion: (lambda args (list 'my-list-of-arguments args)) +Optional arguments: + + [(lambda (x : y) (list x y)) 1] -> (1 nil) + [(lambda (x : y) (list x y)) 1 2] -> (1 2) + .SS Operator op .TP @@ -4855,11 +4865,13 @@ Syntax: Description: The defun operator introduces a new function in the global function namespace. -The function is similar to a lambda, except that <body-form>-s are surrounded -by a named block called nil. The name of this block is the same as the name of -the function, making it possible to terminate the function and return a -value using (return-from <name> <value>). For more information, see the -definition of the block operator. +The function is similar to a lambda, and has the same parameter syntax +and semantics as the lambda operator. + +Unlike in lambda, the <body-form>-s of a defun are surrounded by a block. +The name of this block is the same as the name of the function, making it +possible to terminate the function and return a value using (return-from <name> +<value>). For more information, see the definition of the block operator. A function may call itself by name, allowing for recursion. @@ -6430,7 +6442,7 @@ Certain object types have a custom equal function. .SS Functions search-regex and match-regex -.SS Function make-hash +.SS Functions make-hash, hash .SS Function sethash |