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syntax: add Gleam language support #4045

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Merged
JoeKar merged 12 commits into from
Mar 28, 2026
+69 −0
Merged

syntax: add Gleam language support #4045

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e19c021
syntax: add Gleam language support
HiwarkhedePrasad Mar 15, 2026
992f30c
syntax: improve Gleam syntax highlighting
HiwarkhedePrasad Mar 15, 2026
aa2c965
Refactor Gleam syntax: fix overlaps, expand numbers/operators, add at…
HiwarkhedePrasad Mar 16, 2026
b6657ad
syntax: refine Gleam syntax with review fixes
HiwarkhedePrasad Mar 16, 2026
5f594d1
syntax: restore missing filetype field and remove comments
HiwarkhedePrasad Mar 16, 2026
c733704
syntax: improve tuple highlighting using region
HiwarkhedePrasad Mar 21, 2026
6357c79
syntax: fix indentation, add identifier rule, fix type ordering, expa…
HiwarkhedePrasad Mar 26, 2026
4367c87
add newline before micro judges me again
HiwarkhedePrasad Mar 28, 2026
3338524
style: fix indentation to 4 spaces
HiwarkhedePrasad Mar 28, 2026
fefa5d9
fix: remove trailing whitespace and add final newline
HiwarkhedePrasad Mar 28, 2026
da797ea
fix: ensure final newline at EOF
HiwarkhedePrasad Mar 28, 2026
0700b34
fix: remove extra newline at EOF
HiwarkhedePrasad Mar 28, 2026
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19 changes: 19 additions & 0 deletions runtime/syntax/gleam.yaml
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filetype: gleam

detect:
filename: "\\.gleam$"

rules:
- statement: "\\b(fn|let|case|if|use|import|pub|type|opaque|const|as|assert|panic|todo|echo)\\b"
- identifier: "\\b(Int|Float|String|Bool|List|Option|Result|Nil|BitArray)\\b"
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@Andriamanitra Andriamanitra Mar 16, 2026

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I would remove Nil from here since it's also in constant.

- constant: "\\b(True|False|Nil)\\b"
- operator: "(\\|>|->|<>|==|!=|<=|>=|&&|\\|\\|)"
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@Andriamanitra Andriamanitra Mar 16, 2026

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Most syntaxes choose to use statement for operators (to color them red in the default colorscheme). Most built-in colorschemes color operator with the default (white) color. The list is missing assignment and arithmetic operators.

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@HiwarkhedePrasad HiwarkhedePrasad Mar 16, 2026

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Hi @Andriamanitra , thanks for the great feedback! I've pushed a new commit that addresses all your points:

Rule Overlap: Moved the base identifier rule to the top, so the specific type and constant rules below it can correctly overwrite it.

Built-in Types: Removed Nil from the built-in types list (kept it under constants).

Operators: Moved operators to statement so they highlight correctly, and added the missing arithmetic, assignment, and Gleam-specific float operators.

Numbers: Implemented the robust number regexes from the Python syntax file to handle binary, octal, hex, and scientific notation floats.

Attributes: Added a preproc rule (@[a-zA-Z0-9_]+) to highlight attributes like @external and @deprecated.

- comment:
start: "//"
end: "$"
- string:
start: "\""
end: "\""
skip: "\\\\."
- special: "\\b[0-9]+\\.?[0-9]*\\b"
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@Andriamanitra Andriamanitra Mar 16, 2026

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Numbers should be constant.number. Gleam also supports a pretty wide range of number literals 1 that this regex doesn't cover. The formats seem to be similar to eg. Python so we can probably just copy them from the Python syntax:

micro/runtime/syntax/python3.yaml

Lines 28 to 32 in 42d0ddf

# numbers
- constant.number: "\\b[0-9](_?[0-9])*(\\.([0-9](_?[0-9])*)?)?(e[0-9](_?[0-9])*)?\\b" # decimal
- constant.number: "\\b0b(_?[01])+\\b" # bin
- constant.number: "\\b0o(_?[0-7])+\\b" # oct
- constant.number: "\\b0x(_?[0-9a-fA-F])+\\b" # hex

Footnotes

  1. https://tour.gleam.run/everything/#basics-number-formats ↩

- type: "\\b[A-Z][a-zA-Z0-9_]*\\b"
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@Andriamanitra Andriamanitra Mar 16, 2026

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This overlaps with the definitions for identifier and constant above so those will get colored as type. To fix it you can put this rule before them (later rules are applied on top of earlier ones). It would also make sense to me to change this rule to be identifier, and use type for the built-in types (Int, Float, etc.) that are currently identifier.