Blaise Pascal Compiler

The Pascal you love, reimagined for the modern era.

Blaise is a next-generation Object Pascal compiler built from the ground up to eliminate decades of legacy baggage. It prioritizes developer productivity, memory safety, and high-performance execution.

✨ The Vision

The Object Pascal ecosystem has two options: Embarcadero Delphi (proprietary, Windows-first) and Free Pascal (open source but carrying 30 years of accumulated complexity — five language modes, five string types, and thousands of include files).

This compiler takes a different approach:

• One language mode. No {$mode} switches; no legacy dialect support.

• One string type. UTF-8 reference-counted string and 0-based indexing. RawBytes for binary data.

• One memory model. Automatic reference counting applies uniformly to strings, classes, and interfaces. No manual/auto split between TObject and TInterfacedObject; [Weak] breaks cycles. Free is retained as a synonym for immediate release.

• Clean interfaces. No COM GUIDs; interface dispatch via compile-time vtable mapping.

• Reified generics. Monomorphization at compile time — no type erasure.

• Modern build system. PasBuild with project.xml; no makefiles.

• First-class debugger. OPDF is the default debug format; DWARF is not required.

See docs/design.adoc for the full architecture and implementation plan.

The result — A modern, cross-platform Object Pascal compiler targeting native code via two backends: a direct native x86-64 code generator (the default since v0.12.0) and QBE (now opt-in via --backend qbe). Single language mode, single string type, zero-GUID interfaces, reified generics, and first-class OPDF debug format support — including full source-level debugging of incrementally-compiled multi-unit programs.

🚀 Project Status

• Self-Hosting: Yes. Blaise bootstraps and recompiles itself with byte-for-byte fixpoint. FPC is no longer required — the entire toolchain runs on Blaise alone.

• Testing: 4977+ tests and growing (Test-Driven Development from day one). The test suite itself compiles under Blaise, and runs in CI on both Linux and FreeBSD.

• Backends: Two code-generation backends — a direct native x86-64 backend (the default since v0.12.0) and QBE (opt-in via --backend qbe). Both pass the full fixpoint and test suite.

• Targets: Two targets — Linux x86_64 and FreeBSD x86_64 — with cross-compilation between them in either direction using no external tools or packages: the internal assembler and linker produce the foreign binary directly, and the self-hosting fixpoint is verified on both operating systems.

• Standard library: A growing opt-in stdlib — generics collections, JSON (DOM + parser + writer), SHA-1 and Base64, RFC 4122 UUIDs, TCP sockets, WebSockets, a minimal HTTP/1.1 server, and a blaise.testing unit-test framework.

Phase	Goal	Status
1	Bootstrap pipeline — Hello World on Linux x86_64 via PasBuild	Complete ✅
2	Type system — classes, records, ARC, exceptions	Complete ✅
3	Generics + zero-GUID interfaces	Complete ✅
4	OPDF debug info emission	Complete ✅
5	Self-hosting	Complete ✅
6	Language improvements + expand RTL & StdLib + bug fixing	Ongoing 🔄
7	Native backend feature parity (default backend, internal assembler + linker)	Complete ✅
8	FreeBSD x86_64 target — self-hosting fixpoint + full test suite on FreeBSD, bidirectional cross-compilation	Complete ✅
9	Windows + macOS ARM64 targets	Planned
10	LSP + VS Code extension	Planned
11	Migration analyser for FPC/Delphi codebases	Planned

What Is Dropped From Classic Pascal

Feature	Reason for removal
ShortString, AnsiString, WideString, UnicodeString	Replaced by a single UTF-8 reference-counted string type
with statement	Source of hard-to-diagnose symbol resolution bugs; breaks static analysis
Old-style object types	Use record (stack/value) or class (heap/reference) instead
COM-style interface GUIDs	Interface dispatch via compile-time vtable; GUIDs are unnecessary complexity
Multiple language modes	One dialect, maintained well, beats five dialects maintained poorly
assign, reset, rewrite, blockread	Replaced by a stream-based I/O RTL
TObject vs TInterfacedObject split	One unified class model under automatic reference counting; [Weak] breaks cycles

📢 Community

The core architecture is still being finalised, so the project is not yet accepting code contributions. Feedback on language design, syntax choices, and the future direction of Blaise is very welcome — please use the Discussions tab on GitHub.

Repository Layout

This project uses PasBuild’s multi-module layout. Each subdirectory with a project.xml is an independent module; the root project.xml is the aggregator.

project.xml                       Root aggregator (packaging=pom)
│
├── compiler/                     The compiler binary (packaging=application)
│   ├── project.xml
│   └── src/
│       ├── main/pascal/          uLexer, uParser, uAST, blaise.codegen.qbe, blaise.codegen.native.*, ...
│       │                         plus the RTL units (runtime.*.pas, rtl.platform.*.pas)
│       └── test/pascal/          Test suite (blaise.testing, compiled by Blaise)
│
├── runtime/                      RTL build module (packaging=library)
│   ├── project.xml
│   └── src/
│       └── test/pascal/          Runtime tests (punit, compiled by Blaise)
│
├── stdlib/                       Standard library — opt-in via uses clause
│   ├── project.xml
│   └── src/
│       ├── main/pascal/          sysutils.pas, classes.pas, math.pas, ...
│       └── test/pascal/          Stdlib tests (blaise.testing, compiled by Blaise)
│
├── tools/
│   └── migration-analyser/       FPC/Delphi migration report tool (packaging=application)
│       ├── project.xml           depends on compiler module
│       └── src/
│           ├── main/pascal/
│           └── test/pascal/
│
├── vendor/qbe/                   Vendored QBE backend source (pinned, built from source)
└── docs/                         Design documents and specifications

PasBuild compiles each module to its own target/ subdirectory. Build output is never committed to the repository.

Building

Prerequisites

• A previously released Blaise binary (see releases/)

• PasBuild

• A C compiler (gcc or clang) for building the vendored QBE backend and linking

• GNU make — only for building the vendored QBE backend. The compiler builds and links its RTL from source, so plain compiler use needs no make at all.

Note	FPC is not required. Blaise is fully self-hosting — each release binary compiles the next version. The bootstrap chain starts from the binary in releases/.

Bootstrap from a release

Bootstrapping is a single step — the compiler compiles the RTL from source on demand, so there is no separate runtime build to do first:

# Resolve the newest release binary (substitute the path below for $RELEASE).
RELEASE=$(ls -d releases/v*/ | sort -V | tail -1)blaise   # e.g. releases/v0.12.0/blaise

# Compile the compiler using the release binary (native backend — the default
# since v0.12.0 — needs no external assembler or QBE)
$RELEASE \
  --source compiler/src/main/pascal/Blaise.pas \
  --unit-path compiler/src/main/pascal \
  --unit-path stdlib/src/main/pascal \
  --output compiler/target/blaise

To bootstrap via the opt-in QBE backend instead, build the vendored QBE once (cd vendor/qbe && make) and add --backend qbe — the compiler still drives the assemble + link itself:

$RELEASE \
  --source compiler/src/main/pascal/Blaise.pas \
  --unit-path compiler/src/main/pascal \
  --unit-path stdlib/src/main/pascal \
  --backend qbe --output compiler/target/blaise

Bootstrap a development checkout

The procedure above works while the latest release binary is new enough to compile the current source. Between releases that ceases to hold: once a commit teaches the parser a new feature and a later commit uses it in the runtime/compiler, the release binary can no longer build master directly.

scripts/rolling-bootstrap.sh rebuilds the chain commit-by-commit from the last release binary up to the checked-out revision, producing a working -pre bootstrap binary. See scripts/BOOTSTRAP.adoc for the prerequisite (placing the release binary under releases/) and usage.

Build via PasBuild

PasBuild can drive the full compile and test cycle using a Blaise binary:

pasbuild compile -m blaise-compiler --compiler compiler/target/blaise
pasbuild test -m blaise-compiler --compiler compiler/target/blaise

Run tests

pasbuild test -m blaise-compiler --compiler compiler/target/blaise

Verify self-hosting fixpoint

After any compiler change, verify that the compiler reproduces itself:

./scripts/fixpoint.sh

This generates stage-2 and stage-3 IR and confirms they are identical.

Running the compiler

Once built, the compiler binary is at compiler/target/blaise.

# Compile a single-file program (native backend — default, no external tools)
compiler/target/blaise --source Hello.pas --output Hello

# Compile via the opt-in QBE backend — the compiler drives qbe + the linker
# for you.  No separate assemble/link step, and no archive to pass.
compiler/target/blaise --source Hello.pas --backend qbe --output Hello

# Compile with unit search paths
compiler/target/blaise --source MyApp.pas \
  --unit-path src/units \
  --output MyApp

# Emit QBE IR only (a debugging aid — prints IR instead of building)
compiler/target/blaise --source Hello.pas --emit-ir

Note

--emit-ir / --emit-asm are debugging aids, not build steps: they print the generated IR/assembly and produce no binary. Always build with --output, which lets the compiler own the whole pipeline. In particular, do not hand-link IR with qbe + gcc. The compiler compiles the RTL from source on demand into a target-keyed object cache beside its own binary, so a manual link is both unnecessary and easy to get wrong (it was the cause of issue #180). What the compiler does need is the RTL source to be reachable — via --rtl-src DIR, $BLAISE_RTL_SRC, or a blaise.cfg beside the binary (the release tarballs ship one, so an extracted release works with zero flags).

Examples

Standalone Blaise projects that show the language, the async/fibre runtime, and the standard library used in real applications:

• blaise-microservice-demo — a port of the Java Virtual Threads "API aggregator" demo. An HTTP server whose /aggregate endpoint fans out three concurrent downstream calls that complete in ~2 s wall-clock (not 6 s) via the fibre TTaskGroup nursery and the M:N scheduler, plus a mini-Gatling load generator that ramps to 6000 concurrent virtual users on a handful of OS threads — no framework, no GC. Includes a side-by-side Blaise-vs-Java comparison.

• luhmann — a Zettelkasten note server. Turns a directory of AsciiDoc notes into a linked web of pages served over HTTP, with an interactive note graph and a JSON API, rendering the whole collection concurrently at start-up.

Licence

Apache License v2.0 with Runtime Library Exception. See LICENSE.

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Built with ❤️ for the Pascal community by Graeme.