Improvements after Jens review

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Chemaclass 2021-12-20 23:48:28 +01:00
parent f6c3921900
commit 6d6d62b889

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@ -29,26 +29,26 @@ It is a dialect of Lisp inspired by Phel and Janet.
# More basic examples:
# str will create a string out of all its arguments
(str "Hello" " " "World") # => "Hello World"
(str "Hello" " " "World") #=> "Hello World"
# Math is straightforward
(+ 1 1) # => 2
(- 2 1) # => 1
(* 1 2) # => 2
(/ 2 1) # => 2
(+ 1 1) #=> 2
(- 2 1) #=> 1
(* 1 2) #=> 2
(/ 2 1) #=> 2
# Equality is =
(= 1 1) # => true
(= 2 1) # => false
(= 1 1) #=> true
(= 2 1) #=> false
# You need not for logic, too
(not true) # => false
(not true) #=> false
# Nesting forms works as you expect
(+ 1 (- 3 2)) # = 1 + (3 - 2) => 2
# Phel inherits PHP under the hood, so it can use native PHP (functions and classes) without any additional cost
# by using the `php/` prefix to all PHP native functions.
# Phel inherits PHP under the hood, so it can use native PHP (functions and classes) without
# any additional cost by using the `php/` prefix to all PHP native functions.
# Types
#############
@ -100,153 +100,157 @@ string."
# Collections & Sequences
#############
# Lists are linked-list data structures, while vectors are array-backed.
(type '(1 2 3)) # :list
(type [1 2 3]) # :vector
# Lists are linked-list data structures, while vectors are array-backed
(type '(1 2 3)) #=> :list
(type [1 2 3]) #=> :vector
# A list would be written as just (1 2 3), but we have to quote
# it to stop the reader thinking it's a function.
# Also, (list 1 2 3) is the same as '(1 2 3)
# You can produce a (non-lazy) sequence between a range.
(range 1 10 2) # <- (range from to step)
(range 1 10 2) #=> (range from to step)
(take 4 (range 10))
# Use cons to add an item to the beginning of a list
(cons 4 '(1 2 3)) # => (4 1 2 3)
(cons 4 '(1 2 3)) #=> (4 1 2 3)
# Use push to add, and put to replace an item in a vector
(push [1 2 3] 4) # => (1 2 3 4)
(put [1 2 3] 1 4) # => (1 4 3)
(push [1 2 3] 4) #=> (1 2 3 4)
(put [1 2 3] 1 4) #=> (1 4 3)
# Use concat to add lists or vectors together
(concat [1 2] '(3 4)) # => [1 2 3 4]
(concat [1 2] '(3 4)) #=> [1 2 3 4]
# Use filter, map to interact with collections
(map inc [1 2 3]) # => [2 3 4]
(filter even? [1 2 3]) # => [2]
(map inc [1 2 3]) #=> [2 3 4]
(filter even? [1 2 3]) #=> [2]
# Use reduce to reduce them. The initial-value is mandatory
(reduce + 0 [1 2 3 4])
# => (+ (+ (+ 1 2) 3) 4)
# => 10
#=> (+ (+ (+ 1 2) 3) 4)
#=> 10
(reduce push [] '(3 2 1))
# = (push (push (push [] 3) 2) 1)
# => [3 2 1]
#=> (push (push (push [] 3) 2) 1)
#=> [3 2 1]
# Functions
#############
# Use fn to create new functions. A function always returns its last statement.
(fn [] "Hello World") # => :function
# Use fn to create new functions
# A function always returns its last statement
(fn [] "Hello World") #=> <function>
# You need extra parens to call it
((fn [] "Hello World")) # => "Hello World"
((fn [] "Hello World")) #=> "Hello World"
# You can create a var using def
# You can bind a value to a symbol using def for definition
(def x 1)
x # => 1
x #=> 1
# Assign a function to a var
# Variables provide a way to manage mutable state
(def foo (var 10)) # Define a variable with value 10
# Assign a function to a definition
(def hello-world (fn [] "Hello World"))
(hello-world) # => "Hello World"
(hello-world) #=> "Hello World"
# You can shorten this process by using defn
(defn hello-world [] "Hello World")
# The [] is the list of arguments for the function.
# The [] is the list of arguments for the function
(defn hello [name]
(str "Hello " name))
(hello "Jens") # => "Hello Jens"
(hello "Jens") #=> "Hello Jens"
# You can also use this shorthand to create functions:
# You can also use this shorthand to create functions
(def hello2 |(str "Hello " $1))
(hello2 "Anna") # => "Hello Anna"
(hello2 "Anna") #=> "Hello Anna"
# Functions can pack extra arguments up in a seq for you
(defn count-args [& args]
(str "You passed " (count args) " args: " args))
(count-args 1 2 3) # => "You passed 3 args: @[1 2 3]"
(count-args 1 2 3) #=> "You passed 3 args: @[1 2 3]"
# You can mix regular and packed arguments
(defn hello-count [name & args]
(str "Hello " name ", you passed " (count args) " extra args"))
(hello-count "Jesus" 1 2) # => "Hello Jesus, you passed 2 extra args"
(hello-count "Jesus" 1 2) #=> "Hello Jesus, you passed 2 extra args"
# Maps
#############
# Hash maps have faster lookups but don't retain key order.
(type {:a 1 :b 2 :c 3}) # => :hash-map
(type (hash-map :a 1 :b 2 :c 3)) # => :hash-map
# Hash maps have faster lookups but don't retain key order
(type {:a 1 :b 2 :c 3}) #=> :hash-map
(type (hash-map :a 1 :b 2 :c 3)) #=> :hash-map
# Maps can use any hashable type as a key, but usually keywords are best
# Keywords are like strings with some efficiency bonuses and they start with `:`
(type :a) # => :keyword
(type :a) #=> :keyword
(def stringmap {"a" 1 "b" 2 "c" 3})
stringmap # => {"a" 1 "b" 2 "c" 3}
stringmap #=> {"a" 1 "b" 2 "c" 3}
(def keymap {:a 1 :b 2 :c 3})
keymap # => {:a 1 :c 3 :b 2}
keymap #=> {:a 1 :c 3 :b 2}
# Retrieve a value from a map by calling it as a function
(stringmap "a") # => 1
(keymap :a) # => 1
(stringmap "a") #=> 1
(keymap :a) #=> 1
# Keywords can be used to retrieve their value from a map, too!
(:b keymap) # => 2
(:b keymap) #=> 2
# Don't try this with strings.
# Don't try this with strings
# ("a" stringmap)
# ...Exception: Call to undefined function a()
# Retrieving a non-present key returns nil
(stringmap "d") # => nil
(stringmap "d") #=> nil
# Use put to add new keys to hash-maps
(def newkeymap (put keymap :d 4))
newkeymap # => {:a 1 :b 2 :c 3 :d 4}
newkeymap #=> {:a 1 :b 2 :c 3 :d 4}
# But remember, phel types are immutable!
keymap # => {:a 1 :b 2 :c 3}
keymap #=> {:a 1 :b 2 :c 3}
# Use unset to remove keys
(unset keymap :a) # => {:b 2 :c 3}
(unset keymap :a) #=> {:b 2 :c 3}
# Sets
#############
# A Set contains unique values in random order.
# A Set contains unique values in random order
(type (set 1 2 3)) # => :set
(set 1 2 3 1 2 3 3 2 1 3 2 1) # => (set 1 2 3)
(type (set 1 2 3)) #=> :set
(set 1 2 3 1 2 3 3 2 1 3 2 1) #=> (set 1 2 3)
# Add a member with push
(push (set 1 2 3) 4) # => (set 1 2 3 4)
(push (set 1 2 3) 4) #=> (set 1 2 3 4)
# Remove one with unset
(unset (set 1 2 3) 1) # => (set 2 3)
(unset (set 1 2 3) 1) #=> (set 2 3)
# Test for existence by using the set as a function:
((set 1 2 3) 1) # => 1
((set 1 2 3) 4) # => nil
# Test for existence by using the set as a function
((set 1 2 3) 1) #=> 1
((set 1 2 3) 4) #=> nil
# There are more functions like: count, union, intersection, difference, etc.
# There are more functions like: count, union, intersection, difference, etc
# Useful forms
#############
# Logic constructs in clojure are just macros, and look like everything else
(if false "a" "b") # => "b"
(if false "a") # => nil
# `If` conditionals in phel are special forms
(if false "a" "b") #=> "b"
(if false "a") #=> nil
# Use let to create temporary bindings
(let [a 1 b 2]
(> a b)) # => false
(> a b)) #=> false
# Group statements together with do
(do
@ -262,7 +266,7 @@ keymap # => {:a 1 :b 2 :c 3}
# So does let
(let [name "Urkel"]
(print "Saying hello to " name)
(str "Hello " name)) # => "Hello Urkel" (prints "Saying hello to Urkel")
(str "Hello " name)) #=> "Hello Urkel" (prints "Saying hello to Urkel")
# Use the threading macros (-> and ->>) to express transformations of
# data more clearly.
@ -304,7 +308,7 @@ keymap # => {:a 1 :b 2 :c 3}
# all native functions with the prefix `php/`.
(php/+ 1 2 3)
# With :use you can use different namespaces. Similar as `use` in PHP.
# With :use you can use different namespaces. Similar as `use` in PHP
(ns my\module
(:use \DateTimeImmutable))