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## Copyright (c) Eduardo Julian. All rights reserved.
## This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
## If a copy of the MPL was not distributed with this file,
## You can obtain one at http://mozilla.org/MPL/2.0/.
(;module: {#;doc "Composable extensions to the piping macro |> that enhance it with various abilities."}
lux
(lux (control monad)
(data (struct [list #+ Monad<List> "" Fold<List> "List/" Monad<List>])
maybe)
[compiler #+ with-gensyms Monad<Lux>]
(macro ["s" syntax #+ syntax: Syntax]
[ast])
))
## [Syntax]
(def: body^
(Syntax (List AST))
(s;tuple (s;many s;any)))
(syntax: #export (_> [tokens (s;at-least +2 s;any)])
{#;doc (doc "Ignores the piped argument, and begins a new pipe."
(|> 20
(i.* 3)
(i.+ 4)
(_> 0 i.inc)))}
(case (list;reverse tokens)
(^ (list& _ r-body))
(wrap (list (` (|> (~@ (list;reverse r-body))))))
_
(undefined)))
(syntax: #export (@> [name (s;default "@" s;local-symbol)]
[body body^]
prev)
{#;doc (doc "Gives the name '@' to the piped-argument, within the given expression."
(|> 5
(@> [(i.+ @ @)]))
(|> 5
(@> X [(i.+ X X)])))}
(wrap (list (fold (lambda [next prev]
(` (let% [(~ (ast;symbol ["" name])) (~ prev)]
(~ next))))
prev
body))))
(syntax: #export (?> [branches (s;many (s;seq body^ body^))]
[?else (s;opt body^)]
prev)
{#;doc (doc "Branching for pipes."
"Both the tests and the bodies are piped-code, and must be given inside a tuple."
"If a last else-pipe isn't given, the piped-argument will be used instead."
(|> 5
(?> [i.even?] [(i.* 2)]
[i.odd?] [(i.* 3)]
[(_> -1)])))}
(with-gensyms [g!temp]
(wrap (list (` (let% [(~ g!temp) (~ prev)]
(cond (~@ (do Monad<List>
[[test then] branches]
(list (` (|> (~ g!temp) (~@ test)))
(` (|> (~ g!temp) (~@ then))))))
(~ (case ?else
(#;Some else)
(` (|> (~ g!temp) (~@ else)))
_
g!temp)))))))))
(syntax: #export (!> [test body^] [then body^] prev)
{#;doc (doc "Loops for pipes."
"Both the testing and calculating steps are pipes and must be given inside tuples."
(|> 1
(!> [(i.< 10)]
[i.inc])))}
(with-gensyms [g!temp]
(wrap (list (` (loop [(~ g!temp) (~ prev)]
(if (|> (~ g!temp) (~@ test))
((~' recur) (|> (~ g!temp) (~@ then)))
(~ g!temp))))))))
(syntax: #export (%> monad [steps (s;some body^)] prev)
{#;doc (doc "Monadic pipes."
"Each steps in the monadic computation is a pipe and must be given inside a tuple."
(|> 5
(%> Id/Monad
[(i.* 3)]
[(i.+ 4)]
[i.inc])))}
(with-gensyms [g!temp]
(case (list;reverse steps)
(^ (list& last-step prev-steps))
(let [step-bindings (do Monad<List>
[step (list;reverse prev-steps)]
(list g!temp (` (|> (~ g!temp) (~@ step)))))]
(wrap (list (` (do (~ monad)
[(~ g!temp) (~ prev)
(~@ step-bindings)]
(|> (~ g!temp) (~@ last-step)))))))
_
(wrap (list prev)))))
(syntax: #export (~> [body body^] prev)
{#;doc (doc "Non-updating pipes."
"Will generate piped computations, but their results won't be used in the larger scope."
(|> 5
(~> [int-to-nat %n log!])
(i.* 10)))}
(do @
[g!temp (compiler;gensym "")]
(wrap (list (` (let [(~ g!temp) (~ prev)]
(exec (|> (~ g!temp) (~@ body))
(~ g!temp))))))))
(syntax: #export (&> [paths (s;many body^)] prev)
{#;doc (doc "Parallel branching for pipes."
"Allows to run multiple pipelines for a value and gives you a tuple of the outputs."
(|> 5
(&> [(i.* 10)]
[i.dec (i./ 2)]
[Int/encode]))
"Will become: [50 2 \"5\"]")}
(do @
[g!temp (compiler;gensym "")]
(wrap (list (` (let [(~ g!temp) (~ prev)]
[(~@ (List/map (lambda [body] (` (|> (~ g!temp) (~@ body))))
paths))]))))))
(syntax: #export (case> [branches (s;many (s;seq s;any s;any))] prev)
{#;doc (doc "Pattern-matching for pipes."
"The bodies of each branch are NOT pipes; just regular values."
(|> 5
(case> 0 "zero"
1 "one"
2 "two"
3 "three"
4 "four"
5 "five"
6 "six"
7 "seven"
8 "eight"
9 "nine"
_ "???")))}
(let [(^open "List/") Monad<List>]
(wrap (list (` (case (~ prev)
(~@ (List/join (List/map (lambda [[pattern body]] (list pattern body))
branches)))))))))
|
