Give Control.Matching API better ergonomics.
Given that @tclem and I have found the matcher API frustrating, I've
taken a stab at improving its ergonomics, and I've found some success
in separating composition of matchers from predicate-based narrowing
thereof.
The biggest change here is the elimination of the old `match`
combinator, which proved to be clumsy in that it complected narrowing
and composition. Top-down matching combinators are now written with
the `need` combinator and the `>>>` combinator, which is more readable
and more versatile. Here's a matcher that accepts functions with
Python docstrings:
```haskell
docstringMatcher :: ( Decl.Function :< fs
, [] :< fs
, Lit.TextElement :< fs
, term ~ Term (Sum fs) ann
) => Matcher term term
docstringMatcher = target <*
(need Decl.functionBody
>>> narrow @[]
>>> mhead
>>> narrow @Lit.TextElement
>>> ensure Lit.isTripleQuoted))
```
Pretty readable, right? Each step of the tree regular expression -
choosing function bodies, ensuring said bodies are lists, examining
the first element, and choosing only TextElements containing
triple-quoted strings - is made implicit. The old way would have
looked something like this:
```haskell
docstringMatcher = target <* match Decl.functionBody
$ narrow
$ matchM listToMaybe
$ target <* ensure Lit.isTripleQuoted
```
which is a good deal more disorganized and less flexible
in the quite-common case of applying functions during a
matching pass. Separating the act of composition from
function application is a big win here.
Further comments are inline.
2018-11-03 02:25:29 +03:00
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{-# LANGUAGE TypeOperators, TypeFamilies #-}
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module Matching.Python.Spec (spec) where
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import Control.Arrow
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import Control.Matching
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import Data.Abstract.Module
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import Data.List
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import Data.Sum
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import qualified Data.Syntax.Declaration as Decl
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import qualified Data.Syntax.Literal as Lit
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import qualified Data.Syntax.Statement as Stmt
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import Data.Text (Text)
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import SpecHelpers
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-- This gets the Text contents of all integers
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docstringMatcher :: ( Decl.Function :< fs
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, [] :< fs
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, Lit.TextElement :< fs
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, term ~ Term (Sum fs) ann
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) => Matcher term (TermF Decl.Function ann term)
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docstringMatcher =
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narrowF <* (Decl.functionBody
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2018-11-04 22:46:19 +03:00
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.>> narrow @[]
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Give Control.Matching API better ergonomics.
Given that @tclem and I have found the matcher API frustrating, I've
taken a stab at improving its ergonomics, and I've found some success
in separating composition of matchers from predicate-based narrowing
thereof.
The biggest change here is the elimination of the old `match`
combinator, which proved to be clumsy in that it complected narrowing
and composition. Top-down matching combinators are now written with
the `need` combinator and the `>>>` combinator, which is more readable
and more versatile. Here's a matcher that accepts functions with
Python docstrings:
```haskell
docstringMatcher :: ( Decl.Function :< fs
, [] :< fs
, Lit.TextElement :< fs
, term ~ Term (Sum fs) ann
) => Matcher term term
docstringMatcher = target <*
(need Decl.functionBody
>>> narrow @[]
>>> mhead
>>> narrow @Lit.TextElement
>>> ensure Lit.isTripleQuoted))
```
Pretty readable, right? Each step of the tree regular expression -
choosing function bodies, ensuring said bodies are lists, examining
the first element, and choosing only TextElements containing
triple-quoted strings - is made implicit. The old way would have
looked something like this:
```haskell
docstringMatcher = target <* match Decl.functionBody
$ narrow
$ matchM listToMaybe
$ target <* ensure Lit.isTripleQuoted
```
which is a good deal more disorganized and less flexible
in the quite-common case of applying functions during a
matching pass. Separating the act of composition from
function application is a big win here.
Further comments are inline.
2018-11-03 02:25:29 +03:00
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>>> mhead
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>>> narrow @Lit.TextElement
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>>> ensure Lit.isTripleQuoted)
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spec :: Spec
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spec = describe "matching/python" $ do
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it "matches top-level docstrings" $ do
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parsed <- parseFile pythonParser "test/fixtures/python/matching/docstrings.py"
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let matched = matchRecursively @[] docstringMatcher parsed
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length matched `shouldBe` 2
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it "matches docstrings recursively" $ do
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parsed <- parseFile pythonParser "test/fixtures/python/matching/docstrings_nested.py"
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let matched = matchRecursively @[] docstringMatcher parsed
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length matched `shouldBe` 3
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