Lispy/stdlib.lspy at master · PradCoder/Lispy · GitHub

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; The Lispy Standard Library
; Clone of Daniel Holden's Standard Library
; This was implemented by Pesara Amarasekera as Practice

; Atoms
(def {nil} {})
(def {true} 1)
(def {false} 0)

; Function Definitions
(def {fun} (\ {f b} {
    def (head f) (\ (tail f) b)
}))

; Unpack List of functions
(fun {unpack f l} {
    eval (join (list f) l)
})

; Pack List for Function
(fun {pack f & xs} {f xs})

; Curried and Uncurried calling
(def {curry} {unpack})
(def {uncurry} {pack})

; Perform Several things in Sequence
(fun {do & l} {
    if (== l nil)
    {nil}
    {last l}
})

; Open new scope
(fun {let b} {
    ((\ {_} b) ())
})

; Logical functions
(fun {not x} {- 1 x})
(fun {or x y} {+ x y})
(fun {and x y} {* x y})

; Miscellaneous Functions
(fun {flip f a b} {f b a})
(fun {ghost & xs} {eval xs})
(fun {comp f g x} {f (g x)})

; First, Second, or Third Item in List
(fun {fst l} { eval (head l) })
(fun {snd l} { eval (head (tail l)) })
(fun {trd l} { eval (head (tail (tail l))) })

; List Length
(fun {len l} {
    if (== l nil)
        {0}
        {+ 1 (len (tail l))}
})

; Nth item in List
(fun {nth n l} {
    if(==n 0)
        {fst l}
        {nth (- n 1) (tail l)}
})

; Last item in List
(fun {last l} {nth (- (len l) 1) l})

; Take N items
(fun {take n l} {
    if (== n 0)
        {nil}
        {join (head l) (take (- n 1) (tail l))}
})

; Drop N items
(fun {drop n l} {
    if (== n 0)
        {l}
        {drop (- n 1) (tail l)}
})

; Split at N
(fun {split n l} {list (take n l) (drop n l)})

; Element of List
(fun {elem x l} {
    if (== l nil)
        {false}
        {if (== x (fst l)) {true} {elem x (tail l)}}
})

; Apply Function to List
(fun {map f l} {
    if (== l nil)
        {nil}
        {join (list (f (fst l))) (map f (tail l))}
})

; Apply Filter to List
(fun {filter f l} {
    if (== l nil)
        {nil}
        {join (if (f (fst l)) {head l} {nil}) (filter f (tail l))}
})

; Fold Left
(fun {foldl f z l} {
    if (== l nil)
        {z}
        {flodl f (f z (fst l)) (tail)}
})

(fun {select & cs} {
    if (== cs nil)
        {error "No selection Found"}
        {if (fst (fst cs)) {snd (fst cs)} {unpack select (tail cs)}}
})

; Default Case
(def {otherwise} true)

(fun {case x & cs} {
    if (== cs nil)
        {error "No Case Found"}
        {if (== x (fst (fst cs))) {snd (fst cs)} {
            unpack case (join (list x) (tail cs))}}
})

; Fibonacci
(fun {fib n} {
    select
        { (== n 0) 0 }
        { (== n 1) 1 }
        { otherwise (+ (fib (- n 1)) (fib (- n 2)))}
})