more fundamental changes

This commit is contained in:
Brian Picciano 2014-10-02 15:08:42 -04:00
parent aeb5497f61
commit 7248a929bf

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@ -59,49 +59,50 @@ This evaluates to list whose elements are a function and two numbers:
(":+" 1 2)
```
A list prefixed with a `:` calls the first element as a function with the rest
of the elements as arguments. This evaluates to the number 5:
A list whose first element is a `:` calls the second element as a function with
the rest of the elements as arguments. This evaluates to the number 5:
```
:(":+" 1 2)
(":" ":+" 1 2)
```
A bare string (lacking in `"`) is a shortcut for that string prefixed by a `:`.
This is equivalent to the above:
A bare `:` or `.` string (lacking in `"`) is a shortcut for `":"` or `"."`,
respectively. An otherwise bare string is a shortcut for that string prefixed by
a `:`. This is equivalent to the previous example:
```
:(+ 1 2)
(: + 1 2)
```
The `fn` function can be used to define a new function. This evaluates to an
anonymous function which adds one to its argument and returns it:
The `fn` function can be used to define a new function. Note the `.` instead of
`:`. We'll cover that in a bit. This evaluates to an anonymous function which
adds one to its argument and returns it:
```
:(fn [x]
:(+ x 1))
(. fn [x]
(: + x 1))
```
The `def` function can be used to bind some value to a new variable. Note the
`.` instead of `:`. We'll cover that in a bit. This defines a variable `foo`
which evaluates to the string `"bar"`:
The `def` function can be used to bind some value to a new variable. This
defines a variable `foo` which evaluates to the string `"bar"`:
```
.(def foo "bar")
(. def foo "bar")
```
This defines a variable `incr` which evaluates to a function which adds one to
its argument:
```
.(def incr
:(fn [x]
:(+ x 1)))
(. def incr
(. fn [x]
(: + x 1)))
```
This uses `defn` as a shortcut for the above:
```
.(defn incr [x]
:(+ x 1))
(. defn incr [x]
(: + x 1))
```
There are also maps. A map's keys can be any value(?). A map's values can be any
@ -109,28 +110,35 @@ value. This evaluates to a map with 2 key/val pairs:
```
{ "foo" foo
"bar" :(incr 4) }
"bar" (: incr 4) }
```
`.` is the half-evaluator. It only works on lists, and runs the function given
in the first argument with the unevaluated arguments (even if they have `:` in
front). You can generate new code to run on the fly (macros) using the normal
`fn`. This evaluates to a `let`-like function, except it forces you to use the
capitalized variable names in the body (utterly useless):
in the first argument with the unevaluated arguments (even if they have `:`).
You can generate new code to run on the fly (macros) using the normal `fn`. This
evaluates to a `let`-like function, except it forces you to use the capitalized
variable names in the body (utterly useless):
```
.(defn caplet [mapping body...]
# elem-map maps over every element in a list, embedded or otherwise
::(elem-map
:(fn [x]
:(if (mapping :(slice x 1))
(capitalize x)
#
# eval evaluates a given value (either a string or list). It has been
# implicitely called on all examples so far.
#
# elem-map maps over every element in a list, embedded or otherwise
#
# capitalize looks for the first letter in a string and capitalizes it
#
(. defn caplet [mapping body...]
(. eval (: elem-map
(. fn [x]
(. if (: mapping (: slice x 1))
(: capitalize x)
x))
body))
#Usage
.(caplet [foo "this is foo"
dog "this is dog"]
:(println Foo)
:(println Dog))
(. caplet [foo "this is foo"
dog "this is dog"]
(: println Foo)
(: println Dog))
```