Data.Text.Prettyprint.Location

This module implements types and functions to track and highlight locations in source files.

Source position

data Pos

A point in a source file as a line number, a column number and character offset from the beginning of the file. The line and column number start at 1, the offset starts at 0.

Constructors

Pos

Fields

• posFile :: !FilePath
• posLine :: !Int
• posCol :: !Int
• posOffset :: !Int

Instances

Eq Pos

Two positions are equal if they point in the same file with the same offset.

Defined in Data.Text.Prettyprint.Location

Methods

(==) :: Pos -> Pos -> Bool

(/=) :: Pos -> Pos -> Bool

Show Pos

Defined in Data.Text.Prettyprint.Location

Methods

showsPrec :: Int -> Pos -> ShowS

show :: Pos -> String

showList :: [Pos] -> ShowS

fromOffset :: Monad m => (FilePath -> m Text) -> FilePath -> Int -> m Pos

Constructs a complete Pos from the source file and a character offset. Will throw an error if the file is too short.

The function passed as first argument is used to retrieve the text of the source file. It can be made, for example, to work with a cache to avoid reading the same source file multiple times.

Source span

data Span

A piece of source file, starting at spanStart and spanning spanLen characters.

Constructors

Span

Fields

• spanStart :: !Pos
• spanLen :: !Int

Instances

Eq Span

Defined in Data.Text.Prettyprint.Location

Methods

(==) :: Span -> Span -> Bool

(/=) :: Span -> Span -> Bool

Show Span

Defined in Data.Text.Prettyprint.Location

Methods

showsPrec :: Int -> Span -> ShowS

show :: Span -> String

showList :: [Span] -> ShowS

Semigroup Span

Defined in Data.Text.Prettyprint.Location

Methods

(<>) :: Span -> Span -> Span

sconcat :: NonEmpty Span -> Span

stimes :: Integral b => b -> Span -> Span

mergeSpan :: Span -> Span -> Span

Merge two Spans into one covering both.

For example, merging:

int main () { mldkd; }
    ^^^^

and:

int main () { mkdkd; }
              ^^^^^

results in:

int main () { mkdkd; }
    ^^^^^^^^^^^^^^^

Rendering

displayPos :: Pos -> Text

Shows a Pos in a standard format.

>>> displayPos Pos { posFile = "Foo.hs", posLine = 8, posCol = 3, posOffset = 54 }
"Foo.hs:8:3"

renderPos :: Monad m => (FilePath -> m Text) -> Pos -> m Text

Highlights a point in the source code with a caret, like so:

int main () { mldkd; }
              ^

The function passed as first argument is used to retrieve the text of the source file. It can be used, for example, to work with a cache to avoid reading the same source file multiple times.

renderPosIO :: Pos -> IO Text

Specialised version of renderPos that uses readFile to retrieve the source text.

renderSpan :: Monad m => (FilePath -> m Text) -> Span -> m Text

Highlights the piece of source code designated by the Span.

If it spans a single line, it is rendered like so:

int main () { mldkd; }
              ^^^^^

If it spans multiple lines, it is rendered like so:

> int main() {
>  int x = 0;
>  int y = 1;
>  foo(x,y);
> }

It may throw an error if the source file is too short.

The function passed as first argument is used to retrieve the text of the source file. It can be used, for example, to work with a cache to avoid reading the same source file multiple times.

renderSpanIO :: Span -> IO Text

Specialised version of renderSpan using readFile to retrieve the source text.